section-ii logic of inorganic reactions types of...

SECTION-IILOGIC OF INORGANIC REACTIONS

TYPES OF INORGANIC REACTIONS

All inorganic reactions fall into any one of the following two categories.(i) Metathesis (ii)Redox

(A) METATHESIS:The reaction in which there is no change of Oxidation Number(ON) of any element is

called a metathesis reaction.Some common metathesis types of reactions are discussed below.

(i) Double Replacement (Ion Exchange) Reaction:

This involves the reaction between two substances (which are mostly soluble in water)in which the basic and acid parts (radicals) of two substances get exchanged. That means thebasic part of one substance joins with the acid part of the other substance and vice versa.

Double Replacement reaction is again of two types.(a)neutralisation(acid-base reaction) reaction(b)precipitation reaction

Neutralisation: An acid reacts with a base(alkali) to produce a salt and water. The sourtaste of acid and bitter(soda like) taste of alkali kill each other and a salty taste is found in theproduct.

NaOH + HCl --------> NaCl + H2O

KOH + H2SO

4 --------> K

2SO

4 + H

2O

Ca(OH)2 + HNO

3 --------> Ca(NO

3)

2 + H

2O

In all these cases you find that the ON of none of the elements has undergone any change. Sothese are metathesis reactions.

IMPORTANT: Note that in this chapter, you do not have to balance any equation. Our purposeis to know what products are formed during a reaction and why they are formed. In otherwords, we have to develop the logic of the reaction as to why a particula set of products areformed and why not any other products are formed. So you are categorically advised not tobalance the equations throughout this chapter.

Precipitation: When two soluble substances undergo double replacement reaction andone of the products is insoluble and appears as a precipitate, it is called precipitation reaction.Look to this example.

AgNO3 HCl AgCl HNO3+ +

Here in this double replacement reaction, AgCl appears as a curdy white precipitate. Thereforeit is called a precipitation reaction.

Let us take some more examples.

+ +Al2(SO4)3 NH4OH Al(OH)3 (NH4)2SO4

CaCl2 (NH4)2CO3 CaCO3 NH4Cl+ +

CuSO4 H2S CuS H2SO4+ +

There are however some reactions which belong both to neutralisation as well as precipitation.See this example.

62 Concepts in Chemistry

Ba(OH)2 H2SO4 BaSO4 H2O+ +(neutralisation and precipitation reaction)

In this case, it is an acid-base reaction (neutralisation) and at the same time it is also a precipitationreaction, since BaSO

4 is an insoluble white precipitate . If you are a beginner in chemical sciences,

use the table on solubility rules given in Chapter-I to know which compounds are soluble inwater which are not. In all these reactions, there is no change in ON of any element.

SAQ 1: Detect wherever there is any mistake in the following equations. Correct them.(Donot balance)

(i)NaOH + H2SO

4 -----> NaSO

4 + H

2O

(ii)Ba(OH)2 + H

3PO

4 -------> BaPO

4 + H

2O

(iii)CrCl3 + NaOH --------> CrOH + NaCl

3

(iv)Bi(NO3)

2 + H

2S ------> BiS + H

2NO

3

While answering the SAQ you must have found that in writing the products of a reaction, youhave to write the formula correctly and not merely exchange the radicals. Again you are madecautious at this stage that balancing equation in this program is not required. If you concentrateon balancing, then you cannot predict the products correctly.

SAQ 2: Write the products of the following reactions. Indicate to which kind of doublereplacement reaction it belongs by giving the symbol, (N) for the neutralisation reaction, (P)for precipitation reaction and (B) for the reaction which falls into both the categories. Referthe table on solubility rules given in Chapter-I to know which one is an insoluble precipitate.

(i)Pb(NO3)

2 + NaCl -------> ? (ii)BaCl

2 + K

2CrO

4 ------->

(iii)KF + CaCl2 ------->? (iv)Pb(CH

3COO)

2 + H

2S ---->?

(v)Ba(NO3)

2 + K

2CO

3 ------>? (vi)FeCl

3 + NH

4OH ----->?

(vii)NaOH + H3PO

4 ----->? (viii)HNO

3 + Al

2O

3 ----->

(ix) MgO + H2SO

4 ------->? (x) Cr

2O

3 + H

3PO

4 ------->?

SAQ 3: What are the products of the following reactions? What type of reactions are these?(i)NH

4OH + H

2SO

4----->? (ii) NH

3 + H

2SO

4 ------->?

(iii)NH4OH + HCl ----->? (iv)NH

3 + HCl ----------->?

(v)NH3 + HNO

3------>?

(ii) Reaction of Nonmetallic Oxides with water:This is another type of metathesis reaction in which the ON does not change for any element.Nonmetallic oxides when react with water give the corresponding acids.eg. SO

3 + H

2O -------------> H

2SO

4

Here SO3 is an oxide of the nonmetal sulphur. When sulphur trioxide reacts with water forms

sulphuric acid (H2SO

4). You know that in the periodic table nonmetals are situated in the right-

upper part. Elements like C, N, O, P, S, Cl, Br, I etc. are called nonmetals. Their oxides arecalled acidic oxides, because these oxides produce acids when react with water. Note also thatfor the same reason, the nonmetallic oxides are called ACID ANHYDRIDES( anhydride meanswater removed. They are formed by the removal of water from acids). This means that when anacid anhydride reacts with water it gives back the same acid from which it is produced. Thefollowing table gives a list of some common nonmetallic oxides(acid anhydrides) and thecorresponding acids.

Logic of Inorganic Reactions 63

non metallic Oxide acid nonmetallic Oxide acid

CO2

H2CO

3N

2O

5HNO

3

(carbon dioxide) (carbonic acid) (dinitrogen pentoxide) (nitric acid)N

2O

3HNO

2Br

2O HOBr

(dinitrogen trioxide) (nitrous acid) (dibromine oxide)(hypobromous acid)SO

2H

2SO

3Cl

2O HOCl

(sulphur dioxide) (sulphurous acid) (dichlorine oxide)(hypochlorous acid)SO

3H

2SO

4Cl

2O

3HClO

2

(sulphur trioxide) (sulphuric acid) (dichlorine trioxide)(chlorous acid)P

2O

5(P

4O

10) H

3PO

4Cl

2O

5HClO

3

(diphosphorus pentoxide) (phosphoric acid) (dichlorine pentoxide)(chloric acid)P

2O

3(P

4O

6) H

3PO

3Cl

2O

7HClO

4

(diphosphorous trioxide) (phosphorous acid) (dichlorine heptoxide)(perchloric acid)NO

2* HNO

2 + HNO

3ClO

2* HClO

2 + HClO

3

(nitrogen dioxide) (nitrous acid + (chlorine dioxide) (chlorous acid + nitric acid) (chloric acid)

As2O

3** H

3AsO

3Mn

2O

7** HMnO

4

(arsenous oxide) (arsenous acid) (dimanganese heptoxide) (permanganic acid)As

2O

5** H

3AsO

4CrO

3** H

2CrO

4

(arsenic oxide) (arsenic acid) (chromium trioxide) (chromic acid)

* NO2 and ClO

2 although are nonmetallic oxides form two acids each and therefore these

oxides are called mixed acid anhydrides. These reactions are not metathesis reactions. Theybelong to redox type of reactions which we shall discuss later.**These are oxides of a metalloid(As) and metals (Mn, Cr) which are also acidic. Theseare given in the above table alongwith nonmetallic oxidesEXCEPTIONS: Note that there are few nonmetallic oxides like CO, NO, N

2O which are

neutral. They do not produce any acid when react with water. In fact they do not react withwater.

SAQ 4: Write the missing species of the following reactions. Also see that if the ON of someelement is changing or not? Pick up the underlined element and find its ON on both thesides. Indicate the ON of that element on both the sides to confirm that it is a metathesisreaction.

(i)P2O

5 + H

2O ---->? (ii) N

2O

5 + H

2O -----> ? (iii) ? + H

2O ----> H

3PO

3

(iv) ? + H2O -----> HClO (v) N

2O

3 + H

2O -------? (vi)Cl

2O

5 + H

2O ----->?

(vii)? + H2O ---->HMnO

4(viii)Cl

2O

7 + H

2O----->? (ix)CrO

3 + H

2O ------->?

SAQ 5: Write the products of the following reactions and indicate the changes in ON. Arethese metathesis reactions?

(i)NO2 + H

2O ----->? (ii)ClO

2 + H

2O -------> ?

SAQ 6: Write the anhydrides of the following acids:

H2SO

4, HNO

2, HClO, H

2CO

3, HClO

4


(iii) Reaction of metallic oxides with water:

We had seen before that non-metallic oxides are mostly acidic in nature. Metallic oxides aremostly basic compounds (bases). There are some metallic oxides which are soluble in water.Such examples are very rare. The common among them are Li

2O, Na

2O, K

2O, Rb

2O, Cs

2O,

CaO, SrO and BaO. When these oxides are treated with water, they dissolve forming theirhydroxides. Such a solution is called an alkali.

e.g Na2O + H

2O ---------> NaOH

CaO + H2O --------> Ca(OH)

2

These are metathesis reactions in which there is no change in case of ON of any element.

While writing the products of the above reaction some students wrongly write like this.

Na2O + H

2O ---------> NaOH + H

2(wrong)

This is because in this equation H is reduced from +1 to 0(reduction) and there is no elementwhich is oxidised (oxidation). This is not possible. Oxidation and reduction go together andone cannot happen without the happening of the other. So remember that whenever you find anoxide reacts with water by way of its dissolution in water, it will form only the hydroxide of themetal. If it does not dissolve, then there is no reaction.

N.B: Note that MgO is slightly soluble on strong heating while other oxides are almost insolublein water.

SAQ 7: Write the products of the following:

(i)K2O + H

2O --------> ? (ii)BaO + H

2O ----->?

(iii) ? +H2O---->Sr(OH)

2(iv)Al

2O

3 + H

2O -------->

(iv) Amphoterism:Substance which reacts both with acid and base is called an amphoteric substance. Oxides andhydroxides of a few metals such as Zn, Al, Sn, Pb, Cr, As, Co, Sb, Be, Si are amphoteric innature. For example, ZnO can react with acid and in this reaction ZnO plays the role of a base toform salt and water.

ZnO(base) + HCl(acid) ------------> ZnCl2 + H

2O

ZnO also can react with a strong base like NaOH or KOH to form salt and water. Here ZnOplays the role of an acid. Note that in such a case the acid radical of the salt contains Zn. Do youremember an acid radical which contains Zn? Yes, it is zincate(ZnO

22-). The salt produced is

sodium zincate.

NaOH(base) + ZnO(acid) --------> Na2ZnO

2 + H

2O

The following table gives a list of the amphoteric metal ions and the names (and formulae) ofthe acid radicals formed from them.


metal/metalloid acid part formed alternative formulaIon with strong alkali

Al3+ AlO2

- (meta-aluminate) [Al(OH)4]-

Zn2+ ZnO2

2- (zincate) [Zn(OH)4]2-

Sn2+ SnO22- (stannite) [Sn(OH)

4]2-

Sn4+ SnO32- (stannate) [Sn(OH)

6]2-

Pb2+ PbO22- (plumbite) [Pb(OH)

4]2-

Pb4+ PbO32- (plumbate) [Pb(OH)

6]2-

Co2+ CoO22- (cobaltate) [Co(OH)

4]2-

Sb3+ SbO2

- (antimonite or stibite) [Sb(OH)4]-

Be2+ BeO22- (berrylate) [Be(OH)

4]2-

Cr3+ CrO2

- (chromite) [Cr(OH)4]-

Si4+ SiO3

2- (silicate) [Si(OH)6]2-

SAQ 8: Write the products of the following reactions. Use the above table for this. Give theON of the metal on either side to confirm that the reaction is metathesis type.

(i) Al(OH)3 + KOH ------->? (ii)SnO + NaOH --------->?

(iii) PbO + NaOH --------->? (iv)SnO2 + KOH --------->?

SAQ 9: Find the mistake in the following equations.(Hint: The formula is wrong somewhere)

(i) Zn(OH)2 + NaOH ------> NaZnO

2 + H

2O (ii)CoO + KOH ----->K

3CoO

2 + H

2O

(iii) Al2O

3 + NaOH ------> Na

2AlO

2 + H

2O (iv)SnO + NaOH -----> Na

2SnO

3 + H

2O

(v) Reactions of carbonates, bicarbonates, sulphites, bisulphites, thiosulphates,sulphides and nitrites with dilute mineral acids

When any one of the above mentioned salts reacts with dilute acids, effervescencetakes place producing a gas. Effervescence is the process of evolution of gas bubbles withhissing sound. Carbonate and bicarbonate salts give CO

2 gas; sulphite, bisulphite and thiosulphate

salts give SO2 gas while sulphide salt gives H

2S gas. Thiosulphate salt produce element sulphur

alongwith SO2 gas. See these examples.

Na2CO

3 + HCl -----------> NaCl + CO

2 + H

2O

CaSO3 + H

2SO

4 ----------> CaSO

4 + SO

2 + H

2O

K2S

2O

3 + HCl -------------> KCl + SO

2 + S + H

2O

(Note that although the above reaction appears to be redox reaction, in the true sense itis a metathesis reaction. There are two types of S atoms in thiosulphate ion namely ON 0 and +4which are retained in the products)

ZnS + H2SO

4 ---------------> ZnSO

4 +H

2S

In all these cases no element suffers any change in ON. These are therefore metathesis reactions.

Nitrite salts produce N2O

3 gas which decomposes at room temperature to give both NO

and NO2. While NO

2 is a reddish brown gas, NO is colourless. Looking to the ultimate products

formed at room temperature in this reaction it belongs to the redox type, although the orignialreaction at low temperature(<00C)is metathesis.


NaNO2 + HCl ----low temp.----> NaCl + N

2O

3 + H

2O (Metathesis)

NaNO2 + HCl ---room temp---> NaCl + H

2O + NO + NO

2 (Redox)

SAQ 10: Predict the products of the following metathesis reactions.

(i)KHCO3 + H

2SO

4 ------->? (ii)Na

2SO

3 + HCl ------>?

(iii)Ca(HSO3)

2 + HCl ----->? (iv)ZnCO

3 + HBr ------>?

(v)Bi2S

3 + HCl --------->? (vi)FeS + H

2SO|(dil)------->?

(vii)CaS2O

3 + H

2SO

4(dil) ------->? (viii)KNO

2 + H

2SO

4(dil.)------>?

(vi) Hydrolysis of nitrides, phosphides, carbides and sulphides

Metallic nitrides, phosphides and carbides undergo easy hydrolysis to produce hydroxide ofthe metal and a gas. Hydrolysis is nothing but the reaction of any substance with water. Anitride salt gives ammonia gas(NH

3), a phosphide salt gives phosphine(PH

3) and carbide salt

gives a hydride of carbon(methane or acetylene). Some metallic sulphides also undergo hydrolysisto produce hydrogen sulphide(H

2S) gas. In all these cases, hydroxides of the metals are formed.

Look at these examples.

Mg3N

2 + H

2O -------------> NH

3 + Mg(OH)

2

AlP + H2O ---------------> PH

3 + Al(OH)

3

In all the cases the ON of elements do not change.

Al4C

3 + H

2O--------------> CH

4 + Al(OH)

3; CaC

2 + H

2O ------> C

2H

2 + Ca(OH)

2

In the first example, we get methane(CH4) gas as the carbide has a valency 4(ON= - 4). The ON

of C in both LHS and RHS are same(- 4) since it is a metathesis reaction. In the second example,we get acetylene(C

2H

2) as the calcium carbide is different from aluminium carbide. In this case

the ON of C is -1 (C2

2-). In acetylene ON of carbon is also -1.

FeS + H2O -------> Fe(OH)

2 + H

2S

Do you remember that when we add black salt(the salt that we use at home for palate) withwater, we get a pungent rotten egg smelling gas(H

2S)? It is because the black salt contains

FeS(alongwith NaCl) which is hydrolysed by water to produce H2S gas.

SAQ 11: Write the products of the following hydrolysis reactions.(i)Aluminium Nitride + water------->? (ii)Calcium phosphide + water---->?(iii)CaC

2 + H

2O ------>? (iv)ZnS + H

2O ----->?

(vii) Thermal decomposition of carbonates and bicarbonates:

Some metallic carbonates are not stable on heating and decompose on heating to produce carbondioxide gas and a residue. For example, CaCO

3 on heating gives CO

2 gas and CaO as residue.

But NaHCO3 decomposes in a different way. It gives CO

2 and H

2O as gases and Na

2CO

3 is

formed as residue. Note that Na2CO

3 is very stable to heat and does not undergo decomposition.

All these are metathesis reactions as no change in ON occurs in any element.

CaCO3 ---------------> CaO + CO

2

NaHCO3-----------------> Na

2CO

3 + CO

2 + H

2O

Note that carbonates of Na, K, Rb and Cs are stable to heat and do not undergo any change..


SAQ 12: What are the products obtained by heating the following substances?

(i)MgCO3 --------->? (ii)KHCO

3 --------->? (iii)Li

2CO

3

(viii) Decomposition of ammonium salts by a base(alkali):

When any ammonium salt is heated with a base(alkali), NH3 gas is evolved. Remember that

you have to heat the reactants.

NH4Cl + NaOH -----heat---------> NH

3 + NaCl + H

2O

(NH4)

2SO

4 + Ca(OH)

2 ----heat--------> NH

3 + CaSO

4 + H

2O

In all these cases the ON of N remains same(-3) so also the ON of all other elements.

SAQ 13: What products will be obtained in the following reactions.

(i)NH4Cl + CaO --heat--->? (ii)(NH

4)

2CO

3 + KOH --heat---->?

(iii)NH4Br + Ba(OH)

2 --heat---->? (iv)(NH

4)

2SO

4 + NaOH --heat--->?

(ix) Thermal decomposition of hydroxides:

Excepting hydroxides of Na, K, Rb and Cs, other hydroxides on strong heating decompose toform the corresponding oxides by losing water.

Al(OH)3 ------heat----> Al

2O

3 + H

2O; Ca(OH)

2 -----heat----> CaO + H

2O

LiOH --------> Li2O + H

2O

SAQ 14: Write the products obtained by heating the following.

(i)Be(OH)2

(ii)Mg(OH)2

(iii)Cr(OH)3

(iv)KOH

(x) Displacement of more volatile acid by a less volatile acid:

Look to the following reactions.

NaNO3 + H

2SO

4 -----heat-----> Na

2SO

4 + HNO

3

When a mixture of nitrate salt and conc. sulphuric acid is strongly heated and distilled we getnitric acid in the distillate. This is because, nitric acid is a more volatile acid(lower boilingpoint) and is displaced by a less volatile acid, sulphuric acid(higher boiling point) from the saltof the more volatile acid(nitrate). Sulphuric acid cannot be prepared by this method by heatinga sulphate salt with conc. HNO

3, because a more volatile acid HNO

3 cannot displace a less

volatile acid H2SO

4 from the salt of the latter.

K2SO

4 + HNO

3 ------heat------> KNO

3 + H

2SO

4(not possible)

SAQ 15: Give the products of the following:

(i)NaCl + H2SO

4(conc.) ------->?(ii)KNO

3 + H

2SO

4(conc.) ----->?

(xi) Complexation reactions:

Radicals like [Fe(CN)6]4-, [Ag(CN)

2]-, [Ag(NH

3)

2]+ etc. are called complex ions which are

parts of compounds called complex or coordination compounds. Complex radicals, by convention,are written inside a square bracket. There are two types of species inside the complex ion-(i) one is the metal ion (ii) and the others are ligands. In ferrocyanide ion, Fe2+ is the metal ionand 6 CN- ions are ligands. Hence the net charge of the complex is 4-. Similarly in diammine


silver(I) complex[Ag(NH3)

2]+, Ag+ is the metal ion and two neutral NH

3 molecules are ligands.

The detailed study on complex compounds will not be done in this book.

All complexation reactions belong to metathesis type in which there is no change in ON of anyelement. Look to these examples.

AgCl + 2 NH3 ( 2NH

4OH) ---------> [Ag(NH

3)

2]Cl (silver diammine chloride) (+ 2H

2O)

Fe(CN)2 + 4 KCN ---------> K

4[Fe(CN)

6](potassium ferrocyanide)

Fe(CN)3 + 3 KCN ---------> K

3[Fe(CN)

6](potassium ferricyanide)

HgI2 + 2KI -----------> K

2[HgI

4] (potassium mercuric iodide)

AgCN + KCN --------> K[Ag(CN)2] (potassium argentocyanide)

CuSO4 + 4NH

3 (4NH

4OH) ------> [Cu(NH

3)

4]SO

4 (+4 H

2O) (cuprammine sulphate)

Ni + 4 CO-----------> [Ni(CO)4] (nickel tetracarbonyl)

Cu2(CN)

2 + 6KCN -----> 2K

3[Cu(CN)

4] (potassium cuprocyanide)

SiF4 + 2HF ------> H

2[SiF

6] (hydrofluosilicic acid)

In all these cases the two reactants get added up to form a complex molecule. The names ofcomplex compounds given inside parenthesis are their common names. The systematic IUPACnames are not given here.

(B) REDOX REACTIONSReaction which involves changes in ON is called redox reactions. One reactant is oxidised andis called the reducing agent(RA)and other gets reduced and is called the oxidising agent(OA).We have worked with a large number of redox equations in the previous sections. You knowthat oxidation and reduction go together. In other words one process cannot occur without theoccurrence of the other. Let us take the example to demonstrate this. Often when a student isasked to write the products of the reaction, MnO

2 + HCl---->?, they answer,

MnO2 + HCl ----> MnCl

2 + H

2O. This is wrong. Look to the changes in the ON.

MnO2 HCl MnCl2 H2O+4 +2

+ +-1 -1

While the ON of Mn is reduced from +4 to +2, nowhere there is oxidation. This is not possible.So the prediction is wrong. Another product is missing. It is Cl

2. So that the ON of Cl is increased

from -1 to 0. MnO2 is the OA and HCl is RA.


+ +-1

Cl2+0

This is called studying the logic of a reaction. The cover page of this book carries this message.If you have not marked it in the cover page, see it now. Every reaction has a logic i.e we canexplain why these products are obtained. Often there is a feeling that the hundreds and thousandsof chemical reactions are to be memorised in an unintelligent manner. This is wrong. We shall,in this book, try to learn the logic at each step and try to disprove the above notion aboutchemical reactions.

Now the question arises how shall you know, just by looking to the reactants, whether thereaction will be a redox type or a metathesis type? We list a few clues for the students to guesswhether a reaction belongs to redox category or not.


(i) First check that the reaction does not fall into any of the eleven metathesis reactionscited before. If not, then it could be a redox reaction.

For example, if the reaction is: AlP + H2O----> ? . This cannot be a redox reaction as we know

that this belongs to a metathesis type under the head, "hydrolysis of nitride, phosphide, carbide etc".

(ii) If one of the reactants is not soluble in water(not assigned with aq. symbol) and hencedoes not produce ions, the reaction might be a redox type. In other words if you find atleast one of the reactants is a gas(g), liquid(l) or solid(s), the reaction can be a redoxtype.

NH3(g) + CuO(s)------>

This cannot be metathesis as the reactants are gas and solid and it does not belong to anycategory of metathesis reactions studied before. Hence it has to be a redox reaction.

(ii) If one of the reactants remains in the uncombined state(elemental) state, the reactionbelongs to redox type.

Cl2(g) + NaOH(aq) ---->?

In this case one of the reactants Cl2 is in the uncombined state. So it has to be a redox reaction.

CuO + H2 -----> ?, This reaction also has to be a redox reaction as one of the reactants

is in uncombined state(H2).

So intelligently you have to first ensure whether the reaction could be metathesis or redox. Ifmetathesis then predict the products as per the discussion made in the previous section onmetathesis reaction. But what could be the products if it is a redox reaction? How can you guessthe products? We shall discuss this aspect little later. Before that we discuss some special typesof redox reactions which bear special names. Note that a majority of redox reactions have nospecial names and simply are branded as redox reactions. But some few belong to specificclasses of redox reactions. These are discussed below.

(i) Displacement Reaction:In this reaction, one element displaces another from its salt. Let us take metal displacementfirst. In the example below, you will find that Zn can displace Cu from CuSO

4, but the reverse

reaction is not possible, i.e Cu cannot displace Zn from ZnSO4.

Ex. Zn + CuSO4 -------------> ZnSO

4 + Cu

Cu ZnSO4 CuSO4 Zn (not possible)+ +

This is because Zn is a more active metal than Cu. A more active metal can displace a lessactive metal from the salt of the less active metal. Could you say what changes in ON havetaken place in the first reaction? Zn is oxidised to Zn2+(ON changes from 0 to +2) while Cu2+ isreduced to Cu(ON changes from +2 to 0). The table below gives the list of a few metals forminga series called Metal Activity Series in which metals are arraned in the order of decreasingactivity. A more active metal can displace a less active metal from the salt of the latter. Hydrogenis taken as standard for comparison and is situated in the intermediate position. Metals lyingbefore hydrogen can displace hydrogen gas from acids while metal lying below hydrogen cannotdisplace hydrogen gas from acids.

Mg + HCl --------> MgCl2 + H

2 , Cu + HCl -------> No reaction


Since Mg lies above H, it can displace hydrogen gas from HCl whereas Cu lies below H,therefore it cannot displace hydrogen gas from HCl. That is why we have written 'No Reaction'.

METAL ACTIVITY SERIES

Li > K >Cs > Ba > Ca > Na > Mg > Al > Mn > Zn > Cr > Fe > Cd > Co > Ni > Sn >Pb > H > Sb > Bi > As > Cu > Hg > Ag > Pd > Pt > Au

(NB. Many uncommon metals have not been included in the above series)

The first six metals given in this series upto Na are so reactive that they liberate hydrogen gaseven from cold water. Then the other members after Na i.e starting from Mg upto Cd, candisplace H

2 from boiled water or steam(not cold water) and sometimes the metal is to be

heated to red hot conditions. The metals lying after Cd upto Pb are not active to the extent ofdisplacing hydrogen from water in any condition, whether cold or hot. They can displace hydrogenonly from dilute acids. Note that all metals lying above hydrogen can displace hydrogen fromdilute acids.

SAQ 16: Give the conditions of the reaction and predict the products.

(i)Ca + H2O ----->? (ii)Mg + H

2O ------->? (iii)Fe + H

2O------->

(iv)Sn + H2O ------->? (v)Al + H

2O-------->

SAQ 17: Predict the products:

(i)Ni + HCl ----->? (ii)Ag + HCl ------->? (iii)Zn + HBr------->(iv)Fe + HCl -------->? (v)Hg + HCl ----->?

Halogen Activity Series:

The four halogens namely F2, Cl

2, Br

2 and I

2 form a halogen activity series.

F2>Cl

2>Br

2>I

2

F2 is most active while I

2 is least active. In other words, F

2 has the greatest tendency to be

reduced to F - while I2 has the least tendency to be reduced to I-. .All haloges are good oxidising

agents and are themselves reduced to their halide ions(fluoride, chloride, bromide and iodide)easily. Among the halogens, F

2 is reduced to F- most easily. A more active halogen can displace

a less active halogen from the salt of less active halogen. For example

F2 + NaCl --------> NaF + Cl

2,

Here F2 is reduced to F- while Cl- is oxidised to Cl

2.This reaction occurs because F

2 is more

reactive than Cl2.

Note that when the more active halogen is reduced, the less active halogen gets oxidised. HereCl- is oxidised to Cl

2(from -1 to 0).

Cl2 + NaF ---------> No reaction

Since Cl2 is less reactive than F

2, the former cannot displace the latter from the salt of the latter.


SAQ 18: Predict the products:(i)Cl

2 + KI ---->? (ii)I

2+ KBr ----->? (iii)F

2 + KBr ----->?

(iv)Br2 + NaCl ---->? (v) Cl

2 + NaBr -------->?

SAQ 19: Predict the reactions and write the products formed.(i)Cu + HCl ----------------> (ii)K

2O + Mg ------------->

(iii)KCl + Br2 --------------> (iv)FeBr

3 + Cl

2 -------------->

(v)Al + Cr2O

3 -------------> (vi)Hg + H

2SO

4(dil) -------->

(vii)Na + ZnO -----> (viii)AgNO3 + Cu ------->

(ix)Zn + AuCl3 ------>? (x)Fe + Mn

3O

4------->

(ii) Combustion Reactions:Case-I: Complete Combustion:

Combustion or burning of a substance(mostly organic substance) in presence of sufficient quantityof air to form CO

2 and H

2O is called a combustion reaction. It is an exothermic reaction, that

means heat energy is liberated.

CH4(g) + 2O

2 ------------------> CO

2 + 2H

2O + 820 kJ

C6H

12(l) + 9 O

2 ---------------> 6CO

2 + 6H

2O + 4127 kJ

Note that whatever may be the organic compound, on combustion or burning it will prouduceCO

2 and H

2O.

Case-II: Incomplete Combustion:

If the compound does not get enough oxygen, then instead of producing CO2, it will produce a

poisonous gas CO. This is called incomplete combustion.

CH4 + 3

2 O2 ---------> CO + 2H

2O

Besides CO, other vapours like formaldehyde, methyl alcohol etc. are also produced in somecases.

(iii) Synthesis Reaction:

When two elements directly combine to form a compound, it is called a synthesis reaction.

Mg + Cl2 --------------> MgCl

2

In this example, the ON of Mg of changes from 0 to +2, while the ON of Cl changes from0 to-1.

H2 + Cl

2 ------------> HCl

SAQ 20: Give the synthesis reaction for the formation of the following compounds. Showthe changes in ON in each case.(Balancing the equation is not necessary)

(i)NH3

(ii)CO2

(iii)PCl3

(iv)H2O

(iv) Disproportionation Reaction:

If same substance gets oxidised as well as reduced, it is called a disproportionation reaction. Itmay be different elements present in one substance, out of which one element gets oxidised andthe other gets reduced. It may be the same element present in the substance which is oxidised aswell as reduced. See this example of first type.


KClO3 KCl + O2+5 -1-2 0

[R]

[O]

Here the same substance KClO3 gets oxidised and reduced. O is oxidised from -2 to 0 and Cl is

reduced from +5 to -1. Let us take another example of the second type.

Cl2 + NaOH -------> NaCl + NaClO + H

2O

Here the same substance and the same element Cl gets oxidised(from 0 to +1 in NaClO) as wellas reduced (from 0 to -1 in NaCl). Hence both types of reactions shown above belong to thistype of reaction called disproportionation. In such reactions, we do not specify which is oxidisingagent(OA) and which reducing agent(RA) becasue the same species is OA and RA. Let ustake few more examples.

HI -------> H2 + I

2(H is reduced from +1 to 0 while I oxidised from -1 to 0)

Pb(NO3)

2 -----> PbO + NO

2 + O

2(N reduced from +5 to +4 and O oxidised from -2 to

0)

SAQ 21: Write the products of the following reactions. Show the changes in ON. What typeof redox reaction is this?

(i)NO2 + H

2O ------->? (ii)NO

2 + NaOH ----->?

(iii)ClO2 + H

2O ----->? (iv)NaOH + ClO

2 ------->?

(v) Decomposition(Analysis) Reaction:

When a compound is broken down into smaller molecule by the action of heat, light or electricity,it is called a decompositon or Analysis reaction.

Pb(NO3)

2 ------heat-------> PbO + NO

2 + O

2

Can you show the changes in ON? The ON of N changes from +5 to +4 and that of O from -2 tozero.

When lead nitrate is strongly heated we get a reddish brown gas, NO2, in addition to O

2 gas. The

residue obtained is PbO.

HgO ------heat--------> Hg + O2

Na+ Cl

- Na Cl2

Electrolysis

(cathode) (Anode)+

When molten(liquid) NaCl is electrolysed we get Na at cathode and Cl2 gas at anode. This is

decompositon of a compound by electrical energy.

Note that all nitrates except that of alkali metals(Na, K, Rb, Cs) on thermal decomposition givethe reddish brown NO

2 gas, O

2 gas and oxide of the metal. But the alkali metal nitrates give only

O2 and the corresponding nitrite.

NaNO3 -------->NaNO

2 + O

2( and not Na

2O + NO

2 + O

2)


In this case the ON of N changes from +5(NaNO3) to +3(NaNO

2) and that of O changes from

-2 to 0. LiNO3 is an exception to this behaviou which on heating gives Li

2O, NO

2 and O

2 like

other nitrates.

Note that all thermal decomposition(analysis) reactions(under redox category)as explainedabove are also disproportionation reactions. The same substance gets oxidised as well asreduced.

Decomposition of NH4NO

2 and NH

4NO

3:

These two compounds when strongly heated leave no residue. All the products are gaseousand escape out of the reacting vessel. For all these, you have to remember a trick. Removethe maximum number of water molecules from them, whatever residual formula remains,that is the other gaseous product formed.

NH4NO

2 -------> 2H

2O + N

2

In this case, after removing 2H2O molecules, we are left with N

2 gas. The ON of N changes

from -3(NH4+) to 0(N

2) and also from +3(NO

2-) to 0. It is also a disproportionation reaction.

NH4NO

3----------> 2H

2O + N

2O

After removing 2H2O molecules, we are left with the laughing gas, N

2O. This is also a

disproportionation reaction, in which the ON of N changes from -3(NH4

+) to +1(N2O) and from

+5(NO3

-) to +1.

SAQ 22: What happens when:

(i)A mixture of NaNO2 and NH

4Cl solution is heated.

(ii)A mixture of NaNO3 and NH

4Cl solution is heated.

SAQ 23: Indicate which are synthesis, analysis and disproportionation reactions.Show thechanges in ON in each reaction.

(i)HgO ---heat-----> Hg + O2

(ii) Hg + O2 ------> HgO

(iii)KMnO4 --heat----->K

2MnO

4 + MnO

2 + O

2(iv)Cu + O

2 ------> Cu

2O

SAQ 24: Show the changes in ON in the following disproportionation reactions.

(i)Pb(NO3)

2 ------>PbO + NO

2 + O

2(ii)NaNO

3 ---------> NaNO

2 + O

2

(iii) P4 + NaOH ------> PH

3 + NaH

2PO

2(iv)Cl

2 + NaOH--> NaClO

3 + NaCl + H

2O

(vi)Amphoterism:

You remember that in the metathesis reactions we studied a phenomenon called amphoterism.The oxides and hydroxides of a few metals such as Al, Zn, Sn, Pb etc. reacted both with strongacids and strong bases to produce salt and water. Here we also study amphoterism, but this isredox amphoterism. In this case, in stead of metallic oxide or hydroxide, we take the metal andallow it to react with strong base like NaOH or KOH. We get the same salt(known from thetable given in metathesis amphoterism reaction). But we get H

2 gas instead of H

2O. Thus it

becomes a redox reaction.

Zn NaOH Na2ZnO2 H2+ +0 +1 +2 0

We get sodium zincate and hydrogen gas. You can see the ON changes that take place in the


above reaction. Just think what we would have got if ZnO would have been taken instead of Zn.

ZnO + NaOH -------> Na2ZnO

2 + H

2O (metathesis)

We would have got the same sodium zincate but instead of H2 we get H

2O in such case.

SAQ 25: Predict the product in the following reactions. Also show the changes in ON.

(i) Al + NaOH + H2O ------> (ii)Sn + KOH ----->

(iii) Pb + NaOH ------> (iv)Si + NaOH ------>

(vii) Hydrolysis of metallic hydrides:

Metallic hydrides react with water to produce H2 gas and metallic hydroxides.

NaH + H2O NaOH + H2

-1 +1 0

Hydrogen is both oxidised from -1 to 0 and reduced from +1 to 0.

Some Simple Redox Reactions:Some common OAs : MnO

2, PbO

2, Pb

3O

4, KMnO

4, K

2Cr

2O

7, F

2, Cl

2, Br

2, O

2,

HNO3, H

2SO

4, O

3

Some common RAs : H2S, FeSO

4, NH

3, HI, HBr, HI, all metals, I

2, P

4, S, H

2 , CO,

C, SnCl2

Some agents which can act both as RA and OA : H2O

2, SO

2, HNO

2, NO, NO

2,

N2O

(i) MnO2 + HCl ——> MnCl2 + H2O (wrong)


+ +-1 -1

(there is reduction of Mn but no oxidation)

Mn+4O2 + HCl–1 → Mn+2Cl

2 + Cl

20 + H

2O (correct)

( Mn is reduced from +4 to +2 and Cl is oxidized from –1 to 0)(ii) NH

3 + Cl

2 → HCl + N

2

(N is oxidised from -3 to 0 while Cl is reduced from 0 to -1)If excess of NH

3 is used in the above reaction, NH4Cl is formed in stead of HCl

(iii) CuO + H2 Cu + H

2O

(iv) HBr + H2SO

4(conc) SO

2 + Br

2 + H

2O

(v) HNO3(conc) + C NO

2 + CO

2 + H

2O

(vi) CO2+ C 2CO (vii) Cl

2 + KI KCl + I

2

(viii) KMnO4 + H

2SO

4 + FeSO

4

K2SO

4 + MnSO

4 + Fe

2 (SO

4)

3 + H

2O

(the purple colour of KMnO4 is discharged)

(ix) K2Cr

2O

7 + H

2SO

4 + Na

2SO

3 K

2SO

4 + Cr

2 (SO

4)

3 + Na

2SO

2 + H

2O

(the orange colour of potassium dichromate turns green due to chromic sulphate)(x) NH

3 + O

2 N

2 + H

2O (Show the changes in ON in all the cases)


(xi) Cu + HNO3 (conc) Cu(NO

3)

2 + NO

2 + H

2O

(xii) Cu + H2SO

4 (conc.) CuSO

4 + SO

2 + H

2O

Some important hints for prediction:Usually the ON increases from -ve state to 0 and decreases from +ve state to 0.(Exception : Cl decreases from +ve state to -1, Mn from +7 to +2 in acidicmedium, Cr from +6 to +3, Pb and Mn from +4 to +2, Fe from +3 to +2, Hgfrom +2 to +1 and then to 0, Cu from +2 to +1, Sn inreases from +2 to +4, Fefrom +2 to +3, Mn from +2 to +7, Cr from +3 to +6 etc.)

STRATEGY MAKING AND PREDICTING REACTIONS:In this section we shall know how to predict the products of a reaction. If we are given thereactants only, how shall we write the correct products. Often students, particularly the beginnersbelieve that inorganic reactions are to be simply memorised in an unintelligent manner. When thequestion of remembering hundreds of reactions comes, naturally the study of inorganic chemistryoften appears monotonous and boring. In reality it is not so. If you know the logic of a reaction,you are not required to memorise a reaction. The following example will illustrate this point.

Predict the reaction: Al(OH)3 + NaOH ----?

After seeing the reactants, we are immediately reminded of amphoterism that we studied inmetathesis reaction. The produts are sodium meta-aluminate and water.

Al(OH)3 + NaOH ----> NaAlO

2 + H

2O

So we are not supposed to remember the products. It will automatically occur to us when weknow the logic of predicting reactions.

Let us take another example,

H2S(g) + SO

2(g) ------> ?

If you have memorised the products from before, they are S + H2O. But if you are asked why

these products are formed and why not other products? Then you are in trouble. Remember thatevery reaction has a logic i.e why we get these products and why not some others? Let usanalyse the logic of the above reaction.Just looking to the reactants you will be sure that it cannot be a metathesis reaction. Fristlybecause it does not fall into any of the categories of metathesis reaction. Secondly it has gaseousreactants.

S H2O0+4-2

+ +H2S SO2

[O]

[R]In this reaction the ON of S in H

2S has to increase from -2 to a higher value as it cannot

decrease below -2. Therefore the ON of S in SO2 has to decrease from +4 to a lower value.

Since the element is same(S) in both RA and OA which undergo change in ON, the decreaseand increase take place to the same value(0). So the common product formed from them is S.Then to guess the other product from the other elements is easy. The other produt is H

2O. If you

have not understood this, keep patience, you will be given several examples to make yourunderstanding clear.


Before prediction, you should be sure that the reaction given is either a metatheisreaction or a redox reaction. Because these are the only two types of reactions possible. Whenyou look to the reactants, first ensure whether it belongs to any of the categories of metathesisreactions that we had studied before or not.

(i) If both the reactants are soluble in water(associated with aq. symbol, otherwise youhave to see the solubility rules): they will go for double replacement reaction oftenresulting precipitaion.

AgNO3(aq) + HCl(aq) -------> AgCl(s) + HNO

3(aq)

(ii) If one reactant is an acid and the other reactant is a base(oxide or hydroxide of metal),then it will be neutralisation reaction(under double replacement type) to produce saltand water, irrespective of whether one of the reactants is soluble in water or not.

MgO(s) + H2SO

4(aq) --------> MgSO

4 + H

2O(l)

Here we find that even though one of the products is insoluble(s), it forms the products, salt andwater.

(iii) If one of the reactants is an oxide or hydroxide of an amphoteric metal like Al, Zn, Snetc. and the other is a strong base like NaOH/KOH, then the reaction ismetathesis(Amphotersism).

ZnO + KOH -------> K2ZnO

2 + H

2O

(iv) If one reactant is a non-metallic or a soluble metallic oxide and the other reactant iswater, we get the corresponding acid or alkaline hydroxide(metathesis reaction)respectively.

N2O

5 + H

2O -----> HNO

3

CaO + H2O --------> Ca(OH)

2

(v) If one reactant is a carbonate/bicarbonate or sulphite/bisulphite/thiosulphate or sulphideor a nitrite and the other is an acid: In such case we get CO

2, SO

2 ,H

2S and NO

2(alongwith

NO) gas respectively and those are under metathesis reaction.

CaCO3 + HCl --------> CO

2 + CaCl

2 + H

2O

Na2SO

3 + H

2SO

4 -------> Na

2SO

4 + SO

2 + H

2O

ZnS + HCl ------> ZnCl2 + H

2S

(vi) If one reactant is a metallic nitride, phosphide, carbide or sulphide and the other is water:then it is the hydrolysis reaction producing NH

3, PH

3, CH

4(or C

2H

2) and H

2S respectively.

Mg3N

2 + H

2O -----> Mg(OH)

2 + NH

3

AlP + H2O -------> PH

3 +Al(OH)

3and so on.

(vii) If one reactant is ammonium salt and the other reactant is an alkali/base; such mixtureon heating will produce NH

3 gas.

NH4Cl + NaOH ---heat------> NH

3 + NaCl + H

2O

(some students write NH4OH + NaCl as products which is not wrong, but on heating

NH4OH produces NH

3 and H

2O)


(viii) If it is a case of thermal decompositon of carbonate and bicarbonate:CaCO

3 ----heat-------> CaO + CO

2

(ix) If it is a case of thermal decomposition of metallic hydroxide to produce its oxide or

(x) If it is a case of displacement of more volatile acid by a less volatile acid or

(xi) If it is a case of complexation reaction

If you find that the reaction is not a metathesis reaction, you may guess it to be a redox reaction.

A redox reaction should have the following specialities:

(i) The reaction should not belong to any of the metathesis reactions cited above.

(ii) One of the reactants may exist in the gaseous(g), liquid(l) or solid(s) state.

Example : NH3(g) + CuO(s) ------> ?

In this case you find that the reactants are in gaseous and solid state, so it has to be a redoxreaction.

Once you ascertained that the reaction is a redox type then your work is to assign theON of the elements in the reactants. Then you have to guess which element will undergo changein ON and to what values.

In the above example, the ON of N is -3 in LHS and it has to increase as it cannotdecrease below -3. The ON of Cu is +2 in LHS and it has to decrease. Note that the increase anddecrease of ON usually takes place via zero state. Although there are many exceptions, butstudents always should first think of the product to come to zero ON. So the products in thiscase are N

2 and Cu in which both remain in zero oxidation state. Note that H and O will react to

form water and thus they will not undergo any change in ON.

N2 Cu H2O+-3 0+2

+ +0

NH3 CuO[O]

[R]

Let us take another example.

Example : NH3 + Cl

2 -------->?

In this case N is in -3 state and it has to come to 0 state, while Cl is in 0 state and it has todecrease to -1. So the products are HCl and N

2

HCl N2+-3 0-1

+0

NH3 Cl2

[O]

[R]

IMPORTANT: Prediction of products can be made only for simple reactions with logic. Butfor many other complex reactions, prediction is not possible. However when the products areknown the logic of the reaction can be studied. Once the logic is known it becomes easy toremember the products.Now we shall have to predict a large number of simple reactions giving proper logic. For the first


few reactions the products are given, you are required to put forth the logic i.e to say whether itis metathesis or redox? If metathesis, then to which category of the metathesis reaction does itbelong and if it is redox, then you have to show the oxidation and reduction processes by indicatingthe changes in ON of elements. The beginners are required to answer the questions again andagain in regular intervals to build up more confidence. The equations are not balanced and youare not required to balance them either.

SET-I:(i)CuO + H

2SO

4 ------> CuSO

4 + H

2O (ii)N

2 + H

2 ---------------> NH

3

(iii)TiCl4 + Mg --------> Ti + MgCl

2(iv)FeS + H

2SO

4 --------> FeSO

4 + H

2S

(v)N2O

3 + H

2O ---------> HNO

2

Response:(i) Metathesis: Neutralisation(Acid +Base)(ii) Redox(synthesis):N from 0 to -3 and H from 0 to +1(iii) Redox: Displacement; Mg is more active than Ti(iv) Metathesis: reaction of sulphide with dil. mineral acid(v) Metathesis: Reaction of nonmetallic oxide with water

SET-II:(i)CuCO

3 -----heat----> CuO + CO

2(ii)H

2 + Cl

2 ------> HCl

(iii)Na + HCl -------> NaCl + H2

(iv)KOH + HNO3 ------->KNO

3 + H

2O

(v)Na2O + H

2O -------> NaOH

Response:(i) Metathesis: Thermal decomposition of carbonate(ii) Redox: H from 0 to +1 adn Cl from 0 to -1(iii)Redox: Na from 0 to +1 and H from +1 to 0.(iv)Metathesis: Neutralisation(acid + base)(v)Metathesis: Reaction of metallic oxide with water

SET-III:(i)SnO+ H

3PO

4 ------->Sn

3(PO

4)

3 + H

2O (ii)ZnO + NaOH -----> Na

2ZnO

2 +

H2O

(iii)Na2SO

3 + HCl ----->NaCl + SO

2 + H

2O

(iv)Pb(NO3)

2 ---heat-----> PbO + NO

2 + O

2(v)C

2H

6 + O

2 -------->CO

2 + H

2O

Response:

(i) Metathesis: Neutralisation(ii) Metathesis: Amphoterism(iii)Metathesis: reaction of sulphite salt with dilute acid(iv) Redox: (Analysis as well as disproportionation reaction)N from +5 to +4 and O

from -2 to 0.


(v) Redox: Combustion reaction.

In the following SAQs(SAQ 26-32), the products are not given. You are required topredict the products in a logical basis and indicate the main type of reaction (metathesisor redox) and the sub type to which it belongs. You are also required to show thechanges in ON for a redox reaction. Indicate the metathesis reaction by the symbol, Mand redox reaction by symbol, R.

SAQ 26:(i)N

2O

5 + H

2O -------->? (ii)Ba(OH)

2 + HNO

3 ------>?

(iii)Zn(OH)2 + KOH ------>? (iv)AgNO

3 + NaBr----->?

(v)Na2CO

3 + H

2SO

4 ----------?

Hints: (i) M, Reaction of nonmetallic oxide with water(ii) M: Neutralisation(iii) M: Amphoterism(iv) M: Double Replacement,(v) M: Liberation of CO

2 from a carbonate salt

SAQ 27:(i)BaCl

2(aq) + H

2SO

4(aq) ------>? (ii)K

2O + H

2O-------?

(iii)K+ H2O ------->? (iv) Zn + HCl ------>?

(v)CO2 + H

2O ------->?

Hints: (i) M: Double replacement(precipitation)(ii) M:reaction of metalic oxide to form hydroxide(iii) R: Displacement, K is more active than H.(iv) R:Displacement(v) M:Reaction of nonmetallic oxide with water

SAQ 28:(i)Cu + ZnSO

4 ------->? (ii)Al(OH)

3 + H

2SO

4 ------>?

(iii)SnO + NaOH ---->? (iv)H2 + I

2 ------->? (v)MgS + HCl ----->?

Hints: (i) Cu is less active than Zn (ii) M:Neutralisation(iii) M: Amphoterism (iv) R: synthesis(v) M: reaction of sulphide salt with dilute acid

SAQ 29:(i)Zn + KOH ----->? (ii)CaCl

2(aq) + (NH

4)

2CO

3(aq)--------> ?

(iii)SO2 + H

2O ------>? (iv)NH

3 + O

2 ------->?

(v)Ca(OH)3+H

3PO

4 ---->?

Hints: (i)Amphoterism(redox) (ii)M:double replacement(iii)M:reaction of nonmetallic oxide with water(iv)R: N will go from -3 to 0 and O from 0 to -2 (v)M: Neutralisation

SAQ 30:(i)ZnCl

2(aq) + NH

4OH(aq) ------->? (ii)P

2O

5 + H

2O -----?

(iii)Mg3N

2 + H

2O ------->? (iv)NaHCO

3 ----heat----->?

(v)H2O

2 + H

2S ------>?


Hints: (i)M:Double replacement(precipitation)(ii)M:reaction of non-metallic oxide with water(iii)M: hydrolysis of nitride, phosphide, carbide, sulphide(iv):M:Thermal decomposition(v)R: O will go from -1 in peroxide to -2 and S will go from -2 to 0.

SAQ 31:(i)NaHCO

3 + HCl------->? (ii)Bi(NO

3)

3(aq) + H

2S(aq) ------>?

(iii)Cu + dil. H2SO

4 -------> (iv)Cl

2 + KI------->?

(v)PbO2 ----heat---->?

Hint: (i) M:evolution of CO2 from bicarboante

(ii)M:double replacement(ppt.)(iii)Cu lies below H in the metal activity series(iv)halogen displacement(v)R: Oxygen gas will be evolved(Pb will go from +4 to +2)

SAQ 32:(i)FeS + HCl ---->? (ii)Cl

2O

5 + H

2O------>?

(iii)Al(OH)3 + H

3PO

4----->? (iv)NH

3 + CuO ------->?

(v)Fe + Cl2 -------->?

Hints: (i)M:reaction of sulphide with dilute acid,(ii)M:Reaction of nonmetallic oxide with water(iii)M:Neutralisation(iv)R: N will go from -3 to 0 and Cu from +2 to 0.(v)R: synthesis

SAQ 33: Detect the mistakes in the equations and explain(i)Ag + HCl ----->AgCl + H

2

(ii)As2O

3 + H

2SO

4 -----> AsSO

4 + H

2O

(iii)ZnO + NaOH ------> NaZnO2 + H

2O (iv)N

2O

3 + H

2O -------> HNO

3

(v)MnO2 + HCl-------> MnCl

2 + H

2O

Hint: (i) Ag lies below H in the metal activity series(ii) Is it the correct formula of arsenous sulphate(iii) Is the correct formula of sodium zincate?(iv) What acid does N

2O

3 produces with H

2O? The ON of N is +3 in it but +5 in

HNO3. Can it be possible in a metathesis reaction?

(v) The ON of Mn has been reduced from +4 to +2, but nothing has undergoneoxidation. Is it possible in a redox reaction? Cl will be oxidised.

SAQ 34: Predict the products giving proper logic and indicating the name of the reaction type(subtype if any). Show the ON changes in redox reactions.

(i)ZnCO3 + HBr -------->? (ii)NaHCO

3 ------heat------>

(iii)P2O

5 + NaOH ------->? (iv)Ca + H

2O -------->?

(v)NH3 + HCl -------->?

Hints: (i) M:carbonate salt + acid(ii) M:Thermal decompositon


(iii) M:the corresponding acid will be form which will react with base toform the salt and water

(iv) R: Ca will displace H.(v) M: NH

3 being basic substance will react with acid to form salt

SAQ 35:(i)KOH + SnO -------> (ii)PbO + H

2SO

4----->? (iii)Pb + NaOH ------>?

(iv)Ca(NO3)

2 ------heat---->? (v)As(NO

3)

3(aq) + H

2S(aq)------>?

Hints: (i)M:Amphoterism (ii)M:Neutralisation(iii)R: Amphoterism (iv)R:Decomposition of nitrates(v)M:Double Replacement

SAQ 36:(i)Fe(OH)

3 + HNO

3 ------->? (ii)N

2O

5 + KOH ----->?

(iii)Na2O + H

2O ------->? (iv)K + H

2SO

4(dil) ------->?

(v) P4 + O

2------->?

Hints: (i) M:Neutralisation(ii) Acid of N

2O

5 will be formed which reacts with KOH to form the salt.

(iii) M: Reaction of metallic oxide withe water(iv) R: Displacement(v) R: synthesis

SAQ 37:(i)Ba(NO

3)

2(aq) + Na

3PO

4(aq) ------->? (ii)NO

2 + H

2O ------->?

(iii)NaNO3 ----heat--->? (iv)NH

3 + H

2SO

4 -------->?

(v)FeSO3 + HCl ------->?

Hints: (i)M:Double Replacement (ii)R:NO2 is a mixed anhydride

(iii)R:Thermal decompostion of Na,K nitrates(iv)M: salt formation(v)M:reaction of sulphite salt with acid

SAQ 38: Indicate the mistakes if any with proper reasoning.(i)Mg(NO

3)

2 -------> Mg(NO

2)

2 + O

2(ii)PbO

2 + HBr ------> PbBr

2 + H

2O

(iii)FeCl3 + H

2S -------> FeS + HCl (iv)Ag + HCl -------> AgCl + H

2(v)CuSO

4 + K

4[Fe(CN)

6] ------> Cu[Fe(CN)

6]

2 + K

2SO

4Hints: (i) Decompostion of Na, K nitrates takes place in that manner. Other nitrates

produce the reddish brown gas.(ii) The ON of Pb has decreased from +4(PbO

2) to +2(PbBr

2), then where is

the oxidation? So one more product is missing which is formed by theoxidation of HCl.

(iii) It is a redox reaction, Fe changes from +3 to +2 and S from -2 to 0.(iv) Ag lies below H in the metal activity series(v) The formula of cupric ferrocyanide is wrong

SAQ 39: Indicate the mistakes if any with proper reasoning.(i)Na

2O + H

2O ------> NaOH + H

2(ii)Al

2O

3 + NaOH -------> Na

2AlO

2 + H

2O

(iii)N2O

3 + H

2O ----->HNO

3(iv)Sb(NO

3)

3 + H

2S -------> SbS + HNO

3(v)(NH

4)

2SO

4 + NaOH ----heat----> N

2 + Na

2SO

4 + H

2O

Hints: (i)the ON of H has decreased from +1 to 0 and nowhere there is oxidation.(ii)M:Formula of sodium metaaluminate is wrong. Al should be in +3 state(iii)The ON of N is increased from +3 to +5 while there is no reduction.(iv)M:The formula of antimonous sulphide is wrong(v)M:ammonium salt reacts with alkali to give NH

3 not N

2.


100 REACTIONS WITH LOGIC

Below you shall find 100 reactions whose products are given. The equations are not balanced.You are advised to balance the equations by any method you like. The main class of reaction,whether Metathesis(M) and Redox(R) has been indicated in each case. The ON changes arealso given for redox reactions. The prediction of such reactions from the reactants is often notpossible, however if we study the logic of the reaction it becomes easier for us to remember theproducts. Beginners in the secondary level should only look to logic.

1. KOH + MnO2 + O

2 -------> K

2MnO

4 + H

2O (R) (Mn: +4 to +6; O : 0 to -2)

2. C + H2O ------> CO + H

2(R) (C :0 to +2; H : +1 to 0)

3. CO + NaH ------> HCOONa + C (R) ( H: -1 to +1; C: +2 to 0)4. (NH

4)

2S

2O

8 + H

2O -------> NH

4HSO

4 + H

2O

2 (M): (the peroxy linkage -O-O- present

in peroxidisulphate ion gets hydrolysed to H2O

2)

5. Zn + H2SO

4 + NaClO

3 ------> NaCl + Na

2ZnO

2 + Na

2SO

4 + H

2O (R): (Zn: 0 to +2; Cl:

+5 to -1)6. Al + NaNO

3 + NaOH ------> NH

3 + NaAlO

2 + H

2O (R): (Al: 0 to +3; N: +5 to -3)

7. PbSO4 + CaH

2 -------> PbS + Ca(OH)

2 (R): (S: +6 to -2; H: -1 to +1)

8. SOCl2 + H

2O --------> H

2SO

3 + HCl (M)

9. S + NaOH ----------> Na2S

2O

3 + Na

2S + H

2O (R) (S: 0 to +2; S: 0 to -2)

10. Si + NaOH + H2O -----> Na

2SiO

3 + H

2 (R) ( Si: 0 to +4; H: +1 to 0)

11. CaNCN + NaCl + C -------> NaCN + CaCl2 (R) (C: +4 to +2; C: 0 to +2)

12. NaNH2 + H

2O --------> NaOH + NH

3 (M)

13. NaNH2 + CO --------> NaCN + NaOH + NH

3 (M)

14. NaNH2 + N

2O --------> NaN

3 + H

2O (R) : (N: -3 to -1/3; N:+1 to -1/3)

15. KBrO3 + C -------> KBr + CO (R) (Br:+5 to -1; C: 0 to +2)

16. KOH(hot and conc.) + I2 --------> KIO

3 + KI +H

2O (R) : (I: 0 to -1; I: 0 to +5)

17. CuSO4 + KI -----> Cu

2I

2 + K

2SO

4 + I

2 (R)(Cu: +2 to +1; I: -1 to 0)

18. K4[Fe(CN)

6] + K -------> KCN + Fe (R) ( Fe : +2 to 0; K: 0 to +1)

19. Ca(ClO3)

2 + KCl -------> KClO

3 + CaCl

2 (M)

20. KClO3 + HCl -------> KCl + Cl

2 + ClO

2 + H

2O (R) ( Cl: +5 to +4; Cl: -1 to 0)

21. BeO + NaOH ------> Na2BeO

2 + H

2O(M) Amphoterism

22. Be2C + H

2O ------> CH

4 + Be(OH)

2 (M)

23. BaO + Al -------> No reaction (Ba lies before Al in the metal activity series)24. Ca(HCO

3)

2 ----heat----> CaCO

3 + CO

2 + H

2O (M)

25. CaC2 + N

2 ---heat------> CaNCN + C (R) (C:-1 to +4 in CaNCN also to 0 in C; N:0 to

-3)26. CaNCN + H

2O ---------> CaCO

3 + NH

3 (M)

27. CaO + SiO2 ------> CaSiO

3 (M)

28. BaCO3 + C ------> BaO +CO (R) (C: +4 to +2; C: 0 to +2)

29. BaSO4 + C + CaCl

2 -------> BaCl

2 + CaS + CO (R): (S: +6 to -2; C: 0 to +2)

30. B2O

3 + PCl

5 -------> BCl

3 + POCl

3 (M)


31. AlCl3 + H

2O -----> Al(OH)

3 + HCl (M)

32. Al + Na2CO

3 + H

2O ------> NaAlO

2 + H

2 +CO

2(R) : (Al: 0 to +3; H: +1 to 0)

33. SnCl4 + Sn -----> SnCl

2 (R) (Sn: +4 to +2; Sn: 0 to +2)

34. I2O

5 + CO --------->I

2 + CO

2 (R) (I:+5 to 0; C: +2 to +4)

35. SiO2 + Mg --------> Si + MgO (R) Displacement

36. PbO + PbS ------> Pb + SO2 (R) (Pb: +2 to 0; S: -2 to +4)

37. Pb3O

4 + HCl ------> PbCl

2 + Cl

2 + H

2O (R): (Pb: +8/3 to +2; Cl: -1 to 0)

38. NH3 + NaOCl -----> N

2 + NaCl + H

2O (R) (N: -3 to 0; Cl: +1 to -1)

39. KNO3 + H

2SO

4 + FeSO

4 -------> Fe

2(SO

4)

3 + K

2SO

4 + NO + H

2O (R) (N: +5 to +2; Fe:

+2 to +3)40. KMnO

4 + H

2SO

4 + NO ---------> K

2SO

4 + MnSO

4 + HNO

3 + H

2O (R): (Mn: +7 to +2;

N: +2 to +5)41. NO + Cl

2 --------> NOCl (R) (N: +2 to +3; Cl: 0 to -1)

42. NO + NO2 + KOH ------> KNO

2 + H

2O (R) ( N: +2 to +3; N: +4 to +3)

43. SO2 + NO

2 + H

2O ------> H

2SO

4 + NO (R) ( S: +4 to +6; N: +4 to +2)

44. HNO3 + P

4O

10 ------> N

2O

5 + HPO

3 (M) Dehydration of HNO

3 by P

4O

10

45. N2O

5 + I

2 -------> NO

2 + I

2O

5 (R) (N: +5 to +4; I: 0 to +5)

46. HNO2 ---heat-----> HNO

3 + NO + H

2O (R) Dispror: (N:+3 to +5; N: +3 to +2)

47. HNO2 + HI -------> I

2 + H

2O + NO (R) (N: +3 to +2; I: -1 to 0)

48. FeSO4 + H

2SO

4 + HNO

2 -------> Fe

2(SO

4)

3 + NO + H

2O (R) (Fe: +2 to +3; N: +3 to +2)

49. HNO3 ---sunlight -----> NO

2 + H

2O + O

2 (R) (N:+5 to +4; O:-2 to 0)

50. Sn + HNO3(conc) -----> H

2SnO

3 + NO

2 + H

2O (R) (Sn: 0 to +4; N: +5 to +4)

51. Zn + HNO3 (v.dil) -------> Zn(NO

3)

2 + NH

4NO

3 + H

2O (R) (Zn: 0 to +2; N: +5 to -3)

52. PH3 + Cl

2 -----> PCl

5 + HCl (R) (P: -3 to +5; Cl: 0 to -1)

53. CuSO4 + PH

3 -------> Cu

3P

2 + H

2SO

4 (M)

54. PCl3 + 3H

2O --------> H

3PO

3 + 3HCl (M)

55. P4O

10 + C ------> P

4 + CO (R) (P: +5 to 0; C: 0 to +2)

56. H3PO

2 ---heat-----> PH

3 + H

3PO

3 (R) Dispropr. (P: +1 to +3; P: +1 to -3)

57. H3PO

2 + HgCl

2 + H

2O ------> Hg

2Cl

2 + H

3PO

4 + HCl (R) (P: +1 to +5; Hg: +2 to +1)

58. H3PO

3 + CuSO

4 + H

2O-------> H

3OP

4 + Cu + H

2SO

4 (R) (P: +3 to +5; Cu: +2 to 0)

59. As + NaOH ------> Na3AsO

3 + H

2 (R- Ampho.) (As: 0 to +3; H: +1 to 0)

60. As + HNO3(conc.) ------> H

3AsO

4 + NO

2 + H

2O (R) (As: 0 to +5; N: +5 to +4)

61. Na3AsO

4 + HCl + H

2S -------> As

2S

5 + NaCl + H

2O (M)

62. H3AsO

4 + H

2S -------> H

3AsO

3 + S + H

2O (R) ( As: +5 to +3; S: -2 to 0)

63. Sb + HNO3(conc.) -------> H

3SbO

4 + NO

2 + H

2O (R) (Sb: 0 to +5; N: +5 to +4)

64. Sb2O

3 + NaOH --------> NaSbO

2 + H

2O (M- Ampho.)

65. Sb2O

5 + HCl + KI ----------> SbCl

3 + KCl + I

2 + H

2O (R) ( Sb: +5 to +3; I: -1 to 0)

66. SbCl3 + H

2O -------> SbOCl(antimony oxycloride or antimonyl chloride)+ HCl (M)

67. Bi(NO3)

3 ----heat------->: Bi

2O

3 + NO

2 + O

2 (R)

68. Bi2O

5 + H

2SO

4 ---------> Bi

2(SO

4)

3 + H

2O + O

2 (R) (Bi: +5 to +3; O: -2 to 0)


69. MnO2 + H

2SO

4 ----------> MnSO

4 + O

2 + H

2O (R) (Mn: +4 to +2; O:-2 to 0)

70. KMnO4 +H

2SO

4 ---------> K

2SO

4 + MnSO

4 + O

2 + H

2O (R) ( Mn: +7 to +2; O: -2 to 0)

71. Na2O

2 + H

2O ------->NaOH + O

2 (R): O:-2 to 0; O: -1 to -2)

72. Fe3O

4 + HCl -------> FeCl

2 + FeCl

3 + H

2O (M): Fe

3O

4 (FeO.Fe

2O

3)contains both Fe+2

and Fe+3)73. PbS + O

3 ---------> PbSO

4 + O

2 (R) (S: -2 ro +6; O: 0 to -2: note that O

2 is merly an

additional product)74. O

3 + S + H

2O ---------> H

2SO

4 + O

2(R) (S: 0 to +6; O: 0 to -2)

75. K2S + 4S --------> K

2S

5 (R) (S:-2 to -2/5; S: 0 to -2/5)

76. CuS + HNO3(dil.) ------> Cu(NO

3)

2 + NO + S + H

2O (R) (S: -2 to 0; N:+5 to +2)

77. Na2S

5 + HCl --------> NaCl + H

2S + S (R) (opposite of eq. 75)

78. CaSO4 + C --------> CaO + SO

2 + CO

2 (R) (S: +6 to +4; C: 0 to +4)

79. SO2 + H

2O + FeCl

3 ---------> FeCl

2 + H

2SO

4 + HCl (R) (S: +4 to +6; Fe: +3 to +2)

80. KIO3 + H

2SO

3 --------> KHSO

4 + H

2SO

4 + I

2 + H

2O (R) (I: +5 to 0; S: +4 to +6)

81. KClO3 + H

2SO

4(conc.) ------> KHSO

4 + HClO

4 + ClO

2 + H

2O (R-Dispropr. Cl:+5 to +7;

Cl:+5 to +4)82. K

2S

2O

8 + KI ---------> K

2SO

4 + I

2 ( R) (O: -1 to -2; I: -1 to 0) peroxydisulphate has a

peroxy group)83. Na

2S

2O

3 + I

2 --------> Na

2S

4O

6 + NaI (R) (S:+2 to +2.5; I: 0 to -1)

84. FeSO4 ----heat-----> Fe

2O

3 + SO

2 + SO

3 (R) (Fe: +2 to +3; S:+6 to +4)

85. Na2S + Na

2SO

3 + I

2 ------> Na

2S

2O

3 + NaI (R) (S: -2 to +2; S: +4 to +2 and I: 0 to -1)

86. F2 + NaOH -----> NaF + OF

2 + H

2O (R) (F: 0 to -1; O: -2 to +2)

87. ClO2 + NaOH ---------> NaClO

2 + NaClO

3 + H

2O (R- dispropr.) Cl: +4 to +3; Cl: +4 to

+5)88. Ca(OCl)Cl + HCl -------> CaCl

2 + Cl

2 + H

2O (R) (Cl: +1 to 0; Cl: -1 to 0)

89. HClO3 --------> HClO

4 + O

2 + Cl

2 + H

2O (R-dispropr. Cl: +5 to +7; O: -2 to 0; Cl: +5 to 0)

90. F2 + H

2O --------> HF + O

2 + O

3 (R) (F: 0 to -1; O: -2 to 0)

91. NaBiO3 + MnSO

4 + HNO

3 --------> HMnO

4 + Bi(NO

3)

2 + H

2SO

4 + H

2O (R) (Bi: +5 to

+3; Mn: +2 to +7)92. Bi(OH)

3 + Na

2SnO

3-----------> Bi + Na

2SnO

3 + H

2O (R) (Bi: +3 to 0; Sn: +2 to +4)

93. Zn + NaNO2 + NaOH ---------> Na

2ZnO

2 + NH

3 + H

2O (R) (Zn: 0 to +2; N: +3 to -3)

94. K2CrO

4 + H

2SO

4 --------> K

2Cr

2O

7 + K

2SO

4 + H

2O (M)

95. HgI2 + 2KI --------> K

2[HgI

4] (M- Complexation)

96. CuSO4 + K

4[Fe(CN)

6] --------> Cu

2[Fe(CN)

6] + K

2SO

4 (M)

97. K2Cr

2O

7 + HCl ----------> KCl + CrCl

3 + Cl

2 + H

2O (R) (Cr:+6 to =3; C: -1 to 0)

98. K2Cr

2O

7 + H

2SO

4 + H

2O

2 ------> K

2SO

4 + CrO

5 + H

2O (M)

99. K2Cr

2O

7 + KCl + H

2SO

4 -------> K

2SO

4 + CrO

2Cl

2 +H

2O (M)

100. CrO2Cl

2 + NaOH ------> Na

2CrO

4 + NaCl + H

2O (M)


PRACTICE QUESTIONS

50 reactions are given below in each set. You are required to predict the products withproper reasoning, giving its type(sub-type if any) and for redox reaction, you have to show thechanges in ON.

LEVEL-I

SET-I1. FeS + H

2SO

4(dil)-------> 2. CO

2 + H

2O------->?

3. Cr(OH)3 + H

2SO

4 ------->? 4. Na + H

2O ------->?

5. CaO + H2O ------->? 6. BaCO

3 + HCl ------>?

7. Ca3N

2 + H

2O ----->? 8. NH

4Cl + CaO ---heat---->?

9. Cu + AgNO3 ------>? 10. Cl

2 + KI ------>?

11. NH3 + HCl ----->? 12. N

2O

5 + H

2O ------->?

13. Pb(CH3COO)

2(aq) + K

2CrO

4(aq)------>?

14. CaCO3 ----heat---->? 15. Na

2SO

3 + dil. H

2SO

4 ------>?

16. Al + HCl ------->? 17. AgNO3(aq) + NaCl(aq)------>?

18. Al4C

3 + H

2O ------>? 19. CrCl

3(aq) + NH

4OH(aq) ------>?

20. PbO2 ----heat ----->? 21. SO

3 + NaOH------->?

22. Cu + Zn(NO3)

2 ------->? 23. Mg + HCl ------>?

24. MnCl2(aq) + H

2S(aq)---->? 25. H

2 + I

2 ------->?

26. C2H

6 + O

2 ------->? 27. Ca + H

2O------->?

28. Al + Cl2 ------>? 29. Pb(NO

3)

2-----heat----->?

30. Ca(OH)2 + H

2SO

4 ------>? 31. NH

4NO

2 ---heat---->?

32. Mg + SO2 ------->? 33. K

2CO

3 + H

2SO

4(dil)------->?

34. PbO + HBr ------>? 35. AlP + H2O ------->?

36. KClO3 ----heat---->? 37. (NH

4)

2SO

4 + KOH ----heat----->?

38. Al(OH)3 + NaOH------>? 39. Hg

2(NO

3)

2(aq) + HCl(aq) ----->

40. Fe2O

3 + H

2SO

4 ------>? 41. KNO

3 -----heat----->?

42. Fe(red hot) + H2O(steam)----->? 43. Hg(NO

3)

2(aq) + H

2S(aq)------>?

44. NaOH + SnO ------->? 45. Al + Fe2O

3 ------>?

46. SO2 + H

2O------->? 47. Br

2 + KCl ------->?

48. CaCl2(aq) + (NH

4)

2C

2O

4(aq)------>?

49. MnO2 + HBr ----heat--->? 50. H

2O

2 + H

2S ------->?

SET-II1. N

2O

3 + H

2O-------->? 2. Fe

2(SO

4)

3(aq) + NH

4OH(aq)------>?

3. CO2 + Ca(OH)

2------->? 4. NaNO

3(aq) + H

2SO

4(conc.)----->?

5. Sn(OH)2 + KOH------->? 6. P

2O

5 + NaOH------->?

7. Ca3N

2 + H

2O------>? 8. Ca(NO

3)

2--------->?

9. K2O + H

2O-------->? 10. K + H

2O--------->?

11. FeSO4 + H

2SO

4 + H

2O

2------->? 12. MnO + HNO

3 -------->?

13. BiCl3(aq) + H

2S(aq)-------->? 14. Zn + KOH------>?

15. NH4Br + KOH ----heat---->? 16. Hg + CuSO

4 ------->?


17. F2 + NaBr ------->? 18. MnO

2 + HI ------->?

19. Cu + H2SO

4(dil)------>? 20. Cu + H

2SO

4(conc.)-------->?

21. NH3 + H

2SO

4 ------->? 22. NH

4NO

3------heat------>?

23. Ca(OH)2 -----heat---->? 24. H

2S + O

2 ------->?

25. Pb(NO3)

2(aq) + K

2CrO

4(aq)--->? 26. Mg + PbO ------->?

27. MgSO3 + HBr------->? 28. Hg

2(NO

3)

2(aq)+ HCl(aq)----->?

29. Ca + HCl------->? 30. Ag + HCl ------>?31. PbO+ NaOH----->? 32. NaNO

3 ----heat------>?

33. SO3 + KOH----->? 34. Ba(NO

3)

2 + Na

2CO

3------->?

35. Mn3O

4 + Al----->? 36. NH

3 + Cl

2 ------->?

37. NH3 + H

2O----->? 38. KI + H

2O

2 ------>?

39. Na + NH3 ------->? 40. AlCl

3(aq) + NH

4OH(aq)------>?

41. NiCl2(aq) + H

2S(aq)----->? 42. Cl

2 +KF------->?

43. FeSO4(aq) + NaOH(aq)------>? 44 FeSO

4+ H

2SO

4 + Cl

2------->

45. SnCl2 + HgCl

2 ------->? 46. SrCO

3 + H

2SO

4(dil)----->?

47. HgS + O2 -------->? 48. Pb + NaOH------>?

49. Fe(OH)3 + HCl------>? 50. HNO

3(conc) + H

2S------>?

LEVEL-IISET-I:1. S+O

2---------->? 2. BaCO

3------heat--->?

3. PbS+O2-------->? 4. Pb(NO

3)

2(aq)+HCl(aq)------>?

5. HI +H2O

2------>? 6. N

2O

3 + NaOH---->?

7. Al(OH)3+NaOH------>? 8. NaOH+HNO

3----->?

9. ZnO + C-------->? 10. CaO + H2O----->?

11. BaO2 + H

2SO

4 ------->? 12. TiCl

4+Mg------>?

13. Cr(OH)3+ H

2SO

4------>? 14. Ba(OH)

2+CH

3COOH------>?

15. ZnO+KOH-------->? 16. Sn+ KOH-------->?17. PbO

2-----heat---->? 18. HBr + O

3 -------->?

19. Cu + H2SO

4(conc.)------->? 20. Cu + HNO

3(conc.)-----?

21. Sr(NO3)

2(aq) + CaSO

4(aq)---->? 22. HgO + H

2------>?

23. HNO3(conc) + C ------->? 24. P

2O

5 + KOH----->?

25. PbO2 + HCl----->? 26. MgO + H

3PO

4------>?

27. AlP + H2O----->? 28. CaC

2 + H

2O----->?

29. H2S + SO

2 ------->? 30. SnO

2 + HCl------>?

31. Al2S

3 + H

2SO

4 ------->? 32. BaO + O

2 -------->?

33. NaHCO3 ------heat----->? 34. KNO

3 -----heat----->?

35. (NH4)

2CO

3 + NaOH----heat---? 36. NH

4NO

3----heat---->?

37. Al + NaOH +H2O----->? 38. Pb

3O

4 + HCl------>?

39. Pb + HBr------>? 40. Br2 + NaCl----->?

41. Cr(NO3)

2(aq) + NaOH(aq)----->? 42. I

2O

5+H

2O------->?

43. MnCl2 + H

2S------>? 44. NH

3 + H

2SO

4 ------->?

45. HNO3(conc)+H

2S------>? 46. Zn + CuSO

4 ------>?

47. NH3(excess)+ Cl

2------>? 48. Fe(red hot)+H

2O(steam)------>?


49. Cl2O+H

2O------->? 50. Cl

2O

3 +NaOH------>?

SET-II1. NO

2 +NaOH----->? 2. Fe+Cl

2----->?

3. SnCl2+HCl+HNO

3----->? 4. Al

4C

3+H

2O----->?

5. I2+HNO

3(conc.)------->? 6. PI

3+H

2O----->?

7. HNO3+P

2O

5------->? 8. Cl

2+SO

2+H

2O----->?

9. K2O+H

2O----->? 10. HIO

3+HI------->?

11. Cl2O

7+H

2O------>? 12. NaNO

2 +HCl------>?

13. KMnO4+H

2SO

4+H

2S----->? 14. C

3H

6+O

2-------->?

15. Cu+AgNO3------>? 16. SO

2+KOH------->?

17. Na2S

2O

3 +HCl------->? 18. Li+MgO----->?

19. K2Cr

2O

7+H

2SO

4+FeSO

4----->? 20. Cr(OH)

3+NaOH------>?

21. Cr(OH)3+NaOH + H

2O

2------>? 22. Si+NaOH------>?

23. HI +H2SO

4(conc)----->? 24. Pb +KOH-------->?

25. AgNO3 ----heat---->? 26. P

4+HNO

3------>?

27. K2CO

3-----heat---->? 28. KMnO

4-----heat---->?

29. O3+K

4[Fe(CN)

6]+H

2O--->? 30. ZnSO

4(aq)+K

4[Fe(CN)

6](aq)----->?

31. CaH2 + H

2O ----->? 32. Ca + H

2 ----->?

33. Fe3O

4 + H

2 ------>? 34. SOCl

2 + H

2O ------>?

35. BaO2 + H

2O + CO

2 ----->? 36. Al(OH)

3----heat--->?

37. N2O + Cu ------>? 38. CuI

2------------>?

39. AgCl + Hg---->? 40. XeF4 + H

2 -------->?

41. AsH3 + AgNO

3 + H

2O------->? 42. ZnSO

4 ----heat---->?

43. NH4NO

3 + NaOH---heat------->? 44. NaNO

2 + Al + NaOH----heat---->?

45. NH4NO

2 + HCl-------->? 46. FeSO

4 + K

3[Fe(CN)

6]--------->?

47. K4[(Fe(CN)

6] + Cl

2-------->? 48. K

3[Fe(CN)

6] + SO

2 + KOH------->?

49. CrO3 + NaOH------------>? 50. Cu

2(CN)

2 + 6KCN-------->?

SET-III:1. Na

2O

2 + H

2SO

4 ------> 2. (NH

4)

2S

2O

8 + 2H

2O ------->

3. FeSO4 + H

2SO

4 + H

2O

2 -----> 4. Ag

2O + H

2O

2 -------->

5. Cl2 + H

2O

2 ------> 6. PbS + H

2O

2 -------->

7. BeCl2 + Na ------> 8. B + NaOH ------>

9. Si + NaOH -----> 10. S + NaOH ------>11. Zn(OH)

2 + KOH -----> 12. NaOH + NaHCO

3 ------>

13. NaNH2 + C --------->? 14. NaNH

2 + H

2O------->

15. I2 + NaOH(hot and conc.)------> 16. Ca

3N

2 + H

2O ----->

17. BeO + NaOH-----> 18. Be2C + H

2O ------->

19. CaCO3 + CO

2 + H

2O -----> 20. Ca(HCO

3)

2(aq) ---heat---->

21. MgH2 + H

2O -----> 22. CaF

2 + H

2SO

4 ----->

23. Al4C

3 + H

2O ------> 24. B

2O

3 + KOH ----->

25. SiCl4 + H

2O ------> 26. BF

3 + H

2O ------>

27. H3BO

3 ----heat---> 28. B

2O

3 + K ------>

29. P4O

6 + KOH -------> 30. Al

2O

3+C + N

2 ----->


31. AgCl + 2NH3 ------> 32. KNO

3 +KOH + Zn ------->

33. Fe + Al2O

3 ---------> 34. Al + H

2SO

4(conc.)-------->

35. Al2O

3 + C ------> 36. C + HNO

3(conc) ------>

37. CO2 + C ----> 38. PbO +C ------>

39. H2C

2O

4 ----conc.H

2SO

4----> 40. HCOOH----conc.H

2SO

4 ----->

41. Fe + 5CO -----> 42. Fe2O

3 + CO ----->

43. I2O

5 + CO -----> 44. K

2CO

3 + H

2O + CO

2 ------>

45. Si + KOH + H2O ------> 46. SiO

2 + Mg ----->

47. Sn + HNO3(v.dilute)-----> 48. SnCl

4 + Sn ----->

49. FeCl3 + SnCl

2 -----> 49. Sn(OH)

2 + KOH ----->

50. Pb3O

4 + HCl ----->

RESPONSE TO SAQsSAQ 1:(i) NaOH + H

2SO

4 -----> Na

2SO

4 + H

2O (The formula of sodium sulphate is Na

2SO

4)

(ii) Ba(OH)2 + H

3PO

4 -------> Ba

3(PO

4)

2 + H

2O(The formula of barium phosphate is not

BaPO4)

(iii) CrCl3 + NaOH --------> Cr(OH)

3 + NaCl

(The formula of chromic hydroxide and sodium

chloride are wrong in the question)(iv) Bi(NO

3)

2 + H

2S ------> Bi

2S

3 + HNO

3(The formula of Bismuth sulphide and nitric acid

are wrongly written in the question).

SAQ 2: The symbol (s) is given for the product which is formed as insoluble precipitate.(i)Pb(NO

3)

2 + NaCl -------> PbCl

2(s) + NaNO

3(P)

(ii)BaCl2 + K

2CrO

4 -------> BaCrO

4(s) + KCl (P)

(iii)KF + CaCl2 -------> CaF

2(s) + KCl (P)

(iv)Pb(CH3COO)

2 + H

2S ---->PbS(s) + HCH

3COO( more correctly CH

3COOH) (P)

(v)Ba(NO3)

2 + K

2CO

3 ------>BaCO

3(s) + KNO

3(P)

(vi)FeCl3 + NH

4OH ----->Fe(OH)

3(s)+ NH

4Cl (P)

(vii)NaOH + H3PO

4 ----->Na

3PO

4 + H

2O (N)

(viii)HNO3 + Al

2O

3 ----->Al(NO

3)

3 + H

2O (N)

(ix) MgO + H2SO

4 -------> MgSO

4 + H

2O (N)

(x) Cr2O

3 + H

3PO

4 ------->CrPO

4(s) + H

2O (B)

SAQ 3:These are all neutralisation reactions of a base NH3 or NH

4OH with an acid to give salt.

When we take NH4OH we get water besides the salt but when we take NH

3 we get only the salt.

(i)(NH4)

2SO

4 + H

2O (ii)(NH

4)

2SO

4(iii)NH

4Cl + H

2O

(iv)NH4Cl (v)NH

4NO

3

SAQ 4: All these are metathesis reactions and ON does not change.(i)H

3PO

4 (ON=+5) (ii)HNO

3( ON=+5) (iii)P

2O

3(ON=+3)

(iv)Cl2O (ON=+1) (v)HNO

2(ON=+3) (vi)HClO

3(ON=+5)

(vii)Mn2O

7(ON=+7) (viii)HClO

4(ON=+7) (ix)H

2CrO

4(ON=+6)

SAQ 5:(i) NO

2 + H

2O ----->HNO

2 + HNO

3 (The ON of N goes from +4 in NO

2 to +3 in HNO

2

and again the ON of the same N goes from +4 in NO2 to +5 in HNO

3). This is a redox reaction


and hence not a metathesis reaction. Note that this type of redox reaction in which the samesubstance(NO

2) gets oxidised as well as reduced has a separte name, which we shall discuss

later.(ii) ClO

2 + H

2O -------> HClO

2 + HClO

3 (The ON of Cl changes from +4 in ClO

2 to +3

in HClO2 and again the ON of same Cl changes from +4 in ClO

2 to +5 in HClO

3).

SAQ 6: SO3, N

2O

3, Cl

2O, CO

2, Cl

2O

7

SAQ 7:(i)KOH (ii)Ba(OH)2

(iii)SrO (iv)No reaction; since Al2O

3 is insoluble in water

SAQ 8: (i) KAlO2 + H

2O(Al is in +3 ON) (ii)Na

2SnO

2 + H

2O(Sn is in +2 state)

(iii) Na2PbO

2 + H

2O(Pb in +2 state) (iv)K

2SnO

3 + H

2O (Sn is in +4 state)

Write the names of these salts in language from the table given in the text. The ON of the metalis same on both the sides because these are metathesis reactions.

SAQ 9:

(i) Na2ZnO

2 + H

2O(zincate has a valency of 2 while in the question it has been taken as 1)

(ii) K2CoO

2 + H

2O(cobaltate has a valency of 2, not 3)

(iii) NaAlO2 + H

2O(meta-aluminate has a valency of 1, not 2)

(iv) Na2SnO

2 + H

2O(The ON of Sn in LHS is +2 and in the RHS it cannot be +4 as it is a

metathesis reaction).SAQ 10:

(i)K2SO

4 + CO

2 + H

2O (ii)NaCl + SO

2 + H

2O (iii)CaCl

2 + SO

2 + H

2O

(iv)ZnBr2 + CO

2 +H

2O (v)BiCl

3 + H

2S (vi)FeSO

4 + H

2S

(vii)CaSO4 + SO

2+ H

2O+ S (viii)K

2SO

4 + NO + NO

2 + H

2O

SAQ 11:(i)AlN + H

2O --------> Al(OH)

3 + NH

3(ii)Ca

3P

2 + H

2O ----->Ca(OH)

2 + PH

3

(iii)CaC2 + H

2O ------> C

2H

2 + Ca(OH)

2(iv)ZnS + H

2O------>Zn(OH)

2 + H

2S

SAQ 12:(i)MgO+CO

2(ii)K

2CO

3 + CO

2 + H

2O

(iii)Li2O +CO

2(Li

2CO

3 is the only alkali metal carbonate which decomposes on heating).

SAQ 13: (i)NH3 + CaCl

2 + H

2O (ii)NH

3 + K

2CO

3 + H

2O

(iii)NH3 + BaBr

2 + H

2O (iv)NH

3 + Na

2SO

4 + H

2O

SAQ 14: (i)BeO +H2O (ii)MgO+H

2O (iii)Cr

2O

3 + H

2O(iv)No change

SAQ 15: (i)Na2SO

4 + HCl (ii)K

2SO

4 + HNO

3

SAQ 16: (i)(Cold water)Ca(OH)2 + H

2(ii)(boiled water)MgO + H

2

(iii)Fe3O

4(magnetic oxide or ferrosoferric oxide) + H

2

(the reaction takes place with red hot Fe and superheated steam)(iv)No reaction with any form of water (v)(steam)Al(OH)

3 + H

2

SAQ 17: (i)NiCl2 + H

2(ii)No reaction (iii)ZnBr

2 + H

2

(iv)FeCl2 + H

2(v)No reaction

SAQ 18: (i)I2 + KCl (ii)No reaction (iii)Br

2 + KF

(iv)No reaction (v)Br2 + NaCl

SAQ 19: (i)No reaction (ii)No reaction (iii)No reaction (iv)FeCl3 + Br

2

(v)Al2O

3 + Cr (vi)No reaction (vii)Na

2O + Zn


(viii)Cu(NO3)

2 + Ag (ix)ZnCl

2 + Au (x)No reaction

SAQ 20: (i)N2 + H

2 -----> NH

3(ii)C + O

2 ------> CO

2

(iii)P4 + Cl

2 -----> PCl

3(iv)H

2 + O

2 -------> H

2O

(Student is advised to find the changes in ON in all the above cases)SAQ 21:(i) NO

2 + H

2O -----> HNO

3 + HNO

2 [ N goes from +4 to +5(HNO

3) and from +4 to

+3(HNO2)] Hence it is a disproportionation reaction. You know that NO

2 is a mixed

anhydride.

(ii) NO2 + NaOH ----> NaNO

3 + NaNO

2 + H

2O[N goes from +4 to +5(NaNO

3) and from

+4 to +3(NaNO2)]. Note that NaOH reacts with the two acids produced by NO

2(HNO

3

and HNO2) to form the corresponding salts(NaNO

3 and NaNO

2) and water.

(iii) ClO2 + H

2O -----> HClO

2(chlorous acid) + HClO

3(chloric acid) Cl goes from +4 to

+5(HClO3) and to from +4 to +3(HClO

2). Hence it is a disproportionation reaction.

(iv) ClO2 + NaOH -----> NaClO

3 + NaClO

2 + H

2O

NaOH reacts with the two acids produced by ClO2 to produce the corresponding salts and water.

SAQ 22: (i)First there will be double replacment reaction.NaNO

2 + NH

4Cl -----> NH

4NO

2 +NaCl (i)

Then NH4NO

2 on heating will give N

2 and 2H

2O.

NH4NO

2 ----heat ----> N

2 + 2H

2O (ii)

Adding reaction (i) and (ii), we get the overall reaction.NaNO

2 + NH

4Cl -------> N

2 + H

2O + NaCl

(ii) Like (i)NH4NO

3 will be formed first which will decompose on heating to give N

2O.

NaNO3 + NH

4Cl -----> N

2O + H

2O + NaCl

SAQ 23:(i) Ana. and also Dispr.; Hg changes from +2 to 0 and O changes from -2 to 0.(ii) Synth.; Hg changes from 0 to +2 and O changes from 0 to -2(iii) Ana. and also Dispr.; Mn changes from +7 to +6(K

2MnO

4) and +4(MnO

2) and O

changes from -2 to 0. Note that in this reaction there are two reductions and one oxidation.(iv) Syn.; Cu changes from 0 to +1(Cu

2O) while O changes from 0 to -2.

SAQ 24:(i) N from +5 to +4 and O from -2 to 0 (ii)N from +5 to +3 and O from -2 to 0(iii) P from 0 to -3 and P(PH

3) from 0 to +1(NaH

2PO

2): disproportionation

(iv) Cl from 0 to +5(NaClO3) and Cl from 0 to -1(NaCl): disproportionation

SAQ 25:(i)NaAlO

2 +H

2(ii)K

2SnO

3(potassium stannate) + H

2

Note that in metathesis, we get K2SnO

2(potassium stannite)

(iii)Na2PbO

2 + H

2(iv)Na

2SiO

3 + H

2

The student is advised to show the changes in ONs.SAQ 26: All these are metathesis reactions indicated in the hints in the SAQ.

(i)HNO3

(ii)Ba(NO3)

2 + H

2O (iii)K

2ZnO

2 + H

2O

(iv)AgBr(s)+ NaNO3

(v)Na2SO

4 + CO

2 + H

2O

SAQ 27: (i)BaSO4(s) + HCl(aq) (ii)KOH (iii)KOH + H

2

(iv)ZnCl2 + H

2(v)H

2CO

3(carbonic acid)


SAQ 28: (i)No reaction (ii)Al2(SO

4)

3 + H

2O (iii)Na

2SnO

2 + H

2O

(iv)HI(H goes from 0 to +1 and I from 0 to -1) (v)MgCl2 + H

2S

SAQ 29: (i)K2ZnO

2 + H

2(Zn goes from 0 to +2 and H from +1 to 0)

(ii)CaCO3(s) + NH

4Cl(aq) (iii)H

2SO

3(iv)N

2 + H

2O(N from -3 to 0

and O from 0 to -2) (v)Ca3(PO

4)

2 +H

2O

SAQ 30: (i)Zn(OH)2(s) + NH

4Cl (ii)H

3PO

4(iii)Mg(OH)

2 + NH

3

(iv)Na2CO

3 + CO

2 + H

2O (v)H

2O + S

SAQ 31: (i)NaCl + CO2 + H

2O (ii)Bi

2S

3(s) + HNO

3(iii)No reaction

(iv)I2 +KCl (v)PbO + O

2(Pb from +4 to +2 and O from -2 to0)

SAQ 32: (i)FeCl2 + H

2S (ii)HClO

3(iii)AlPO

4 + H

2O

(iv)N2 + Cu +H

2O (v)FeCl

3(Fe from 0 to +3 and Cl from 0 to -1)

SAQ 33: (i)No reaction (ii)As2(SO

4)

3(iii)Na

2ZnO

2

(iv)HNO2

(v)MnCl2 + Cl

2 + H

2O (Cl is oxidised from -1 to 0)

SAQ 34: (i)ZnBr2 + CO

2 + H

2O (ii)Na

2CO

3 + CO

2 + H

2O

(iii)Na3PO

4 + H

2O

(iv)Ca(OH)2 + H

2(the ON of Ca changes from 0 to +2 and H from +1 to 0)

(v)NH4Cl

SAQ 35: (i)K2SnO

2 + H

2O (ii)PbSO

4 + H

2O

(iii)Na2PbO

2 + H

2(The ON of Pb changes from 0 to +2 and H from +1 to 0)

(iv)CaO+NO2 +O

2(The ON of N changes from +5 to +4 and O from -2 to 0)

(v)As2S

3(s) +HNO

3(aq)

SAQ 36: (i)Fe(NO3)

3 + H

2O (ii)KNO

3 + H

2O

(iii)NaOH (iv)K2SO

4 + H

2

(v)P4 + O

2 ------>P

2O

3(limited oxygen) and also P

4 + O

2 -------> P

2O

5(excess

oxygen) (The ON of P changes from 0 to +3 or +5 and of O from 0 to -2)SAQ 37: (i)Ba

3(PO

4)

2(s) +NaNO

3(aq)

(ii)HNO2 + HNO

3 (Redox: Disproportionation, the ON of N changes

from +4 to +5 and +4 to +3)(iii)NaNO

2 + O

2(the ON of N changes from +5 to +3 and O from -2 to 0)

(iv)(NH4)

2SO

4(v)FeCl

2 + SO

2 + H

2O

SAQ 38: (i)MgO+ NO2 + O

2(ii)PbBr

2 + Br

2 + H

2O(ON of Br changes from -1 to 0)

(iii)FeCl2 + HCl + S (iv)No reaction (v)Cu

2[Fe(CN)

6]

SAQ 39: (i)NaOH (ii)NaAlO2 + H

2O (iii)HNO

2(iv)Sb

2S

3 + HNO

3(v)NH

3 + Na

2SO

4 + H

2O

ANSWERS TO PRACTICE QUESTIONS

LEVEL-I

SET-I

1. FeSO4 + H

2S (M: suphide salt with acid)

2. H2CO

3(M:non-metallic oxide with H

2O)

3. Cr2(SO

4)

3 + H

2O (M:Neutralisation)


4. NaOH + H2

(R: Displ.; Na from 0 to +1 and H from +1 to 0)5. Ca(OH)

2(M: metallic oxide with H

2O)

6. BaCl2 + CO

2 + H

2O (M: carbonate salt with acid)

7. Ca(OH)2 + NH

3(M:nitride salt with water)

8. CaCl2 + NH

3 + H

2O (M: ammonium salt with a base)

9. Ag + Cu(NO3)

2(R: Displ.; Ag from +1 to 0 and Cu from 0 to +2)

10. I2 + KCl (R: halogen displ.; Cl from 0 to -1 and I from -1 to 0)

11. NH4Cl (M: Neu., H

2O is not formed because it is NH

3 not NH

4OH)

12. HNO3

(M: nonmetallic oxide with water)13. PbCrO

4(s) + KCH

3COO(CH

3COOK) (M: Double. Repl./ Preci.)

14. CaO + CO2

(M: decomp. of carbonate salt)15. Na

2SO

4 + SO

2 + H

2O (M: sulphite salt with acid)

16. AlCl3 + H

2(R: Displ.;Al from 0 to +3 and H from +1 to 0)

17. AgCl(s) + NaNO3

(M:Double Repl./ Preci.)18. Al(OH)

3 + CH

4(M: carbide with water)

19. Cr(OH)3(s)+NH

4Cl (M:Double Repl./ Preci.)

20. PbO + O2

(R: Pb from +4 to +2 and O from -2 to 0)21. Na

2SO

4 + H

2O (M:SO

3 gives H

2SO

4 which reacts with NaOH)

22. No reaction (Cu lies below Zn in the metal activity series)23. MgCl

2 + H

2(R: Mg from 0 to +2, H from +1 to 0)

24. MnS(s) + HCl (M: Double Repl./ Preci.)25. HI (R:syn.; H from 0 to +1, I from 0 to -1)26. CO

2 + H

2O (R: combustion)

27. Ca(OH)2 + H

2(R: Displ.; Ca from 0 to +2, H from +1 to 0)

28. AlCl3

(R: syn.; Al from 0 to +3, Cl from 0 to -1)29. PbO + NO

2 + O

2(R: Decomp., Dispropr./ N from +5 to +4 and O from -2 to 0)

30. CaSO4 + H

2O(M: Neu)

31. N2 + 2H

2O [Decomp. of NH

4NO

2/ N from -3(NH

4+) to 0 and N from +3(NO

2-) to 0]

32. MgO + S (R: Mg from 0 to +2, S from +4 to 0)33. K

2SO

4 + CO

2 + H

2O (M: carbonate salt with acid)

34. PbBr2 + H

2O (M: Neu.)

35. Al(OH)3+PH

3(M:phoshphide salt with H

2O)

36. KCl + O2

(R: Decomp., Dispropr./Cl from +5 to -1 and O from -2 to 0)37. K

2SO

4 + NH

3 + H

2O (M:ammonium salt with a base)

38. NaAlO2 + H

2O (M: Amphoterism)

39. Hg2Cl

2(s) + HNO

3(M:Double repl./Preci.)

40. Fe2(SO

4)

3 + H

2O (M: Neu.)

41. KNO2 + O

2(R: Decomp. of Na and K nitrate/ N from +5 to +3 and O from -2 to 0)

42. Fe3O

4(Ferrosoferric oxide or magnetic oxide) + H

2

(R: Displ./Fe from 0 to +8/3 and H from +1 to 0)43. HgS(s) + HNO

3(M:Double Repl./Preci.)

44. Na2SnO

2 + H

2O (M: Amphoterism)

45. Al2O

3 + Fe (R: Displ./Al from 0 to +3 and Fe from +3 to 0)

46. H2SO

3(M: nonmetallic oxide with H

2O)


47. No reaction (Br is below Cl in the halogen activity series)48. CaC

2O

4(s)(calcium oxalate) +NH

4Cl (M: Double Repl./Preci.)

49. MnBr2 + Br

2 + H

2O (R: Mn from +4 to +2 and Br from -1 to 0)

50. S + H2O [R: S from -2 to 0 and O from -1(peroxide) to -2(water)]

SET-II:1. HNO

2(M)

2. Fe(OH)3(s)+(NH

4)

2SO

4 (M:Double Repl)

3. CaCO3(s)+H

2O(M: CO

2 forms carbonic acid salt i.e carbonate)

4. HNO3 + Na

2SO

4 (M:Double Repl.)

5. K2SnO

2+H

2O (M: Ampho.)

6. Na3PO

4 + H

2O(P

2O

5 forms the H

3PO

4 and with NaOH forms phoshpate salt)

7. Ca(OH)2 + NH

3(M:hydrolysis of nitride)

8. CaO+NO2+O

2(R: N goes from +5 to +4 and O from -2 to 0)

9. KOH (M: metallic oxide with H2O)

10. KOH + H2(R:Displacement)

11. Fe2(SO

4)

3 + H

2O[R: Fe goes from +2 to +3 and O from -1 in peroxide to -2 in water.

Note : that in every redox reaction FeSO4 takes the help of H

2SO

4 to make it Fe

2(SO

4)

3]

12. Mn(NO3)

2 +H

2O(M: Neu.)

13. Bi2S

3(s)+HNO

3(M: DR/preci)

14. K2ZnO

2 + H

2(R:Amphoterism/ Zn goes from 0 to +2 and H from +1 to 0)

15. KBr + NH3 + H

2O(M: decomposition of ammonium salt by a base)

16. No reaction: Hg lies below Cu17. NaF + Br

2(R: Displacement of halogen)

18. MnI2 + I

2 + H

2O(R: Mn from +4 to +2 and I from -1 to 0)

19. No reaction: Cu lies below H20. CuSO

4 + SO

2 + H

2O(R:Cu from 0 to +2 and S from +6 to +4. Note that conc. H

2SO

4 is

a strong oxidising agent and it is always reduced to SO2 gas. In no case H

2 gas is

displaced from the acid)21. (NH

4)

2SO

4(M: salt formation. NH

3 is a base which reacts with acid to form the salt).

22. N2O + 2H

2O(R: N goes from -3 in NH

4+ to +1 and also N goes from +5 in NO

3- to +1)

23. CaO + H2O(M: decomp. of hydroxides)

24. S +H2O(R: S from -2 to 0 and O from 0 to -2. Note that in every redox reaction, H

2S is

oxidised to S)25. PbCrO

4(s) +KNO

3(M:DR/preci.)

26. MgO + Pb(R: Displacement)27. MgBr

2 + SO

2 + H

2O(M: sulphite salt with acid)

28. Hg2Cl

2(s) + HNO

3(M:DR/preci.)

29. CaCl2 + H

2(R: Ca lies above H)

30. No reaction(Ag lies below H)31. Na

2PbO

2 +H

2O(M:Ampho.)

32. NaNO2 +O

2(R: N from +5 to +3 and O from -2 to 0. Note that NaNO

3 and KNO

3 do not

give NO2 gas like other nitrates)

33. K2SO

4 +H

2O(M: Neu./ SO

3 forms H

2SO

4 which forms sulphate salt with KOH)

34. BaCO3(s) + NaNO

3(M:DR/preci.)


35. Al2O

3 + Mn(R: Displacement)

36. N2 +HCl(R: N from -3 to 0 and Cl from 0 to -1. Note that often students commit mistake

by writing the product NH4Cl only. In such case only Cl is reduced from 0 to -1 but

there is no oxidation. So N2 is formed)

37. NH4OH(M: reaction of a base with water forming its hydroxide)

38. I2 + KOH(R: I from -1 to 0 and O from -1 in peroxide to -2 in KOH)

39. NaNH2(sodium amide) + H

2(R: Na from 0 to +1 and H from +1 to 0. Note that active

metals like Na, K etc. can displace H from even NH3 forming the metal amides)

40. Al(OH)3(s) +NH

4Cl(M:DR/preci.)

41. NiS(s) +HCl(M:DR/preci.)42. No reaction(Cl

2 is below F

2)

43. Fe(OH)2(s)+Na

2SO

4(M:DR/preci.)

44. Fe2(SO

4)

3+HCl(R: Fe from +2 to +3 and Cl from 0 to -1)

45. SnCl4 + Hg

2Cl

2(R: Sn from +2 to +4 and Hg from +2 to +1. Note that SnCl

2 is good

reducing agent and HgCl2 is a good oxidising agent)

46. SrSO4 +CO

2 +H

2O(M: carbonate salt with water)

47. HgO + SO2(R: O from 0 to -2 and S from -2 to +4)

48. Na2PbO

2 + H

2(R: Amphoterism/ Pb from 0 to +2 and H from +1 to 0)

49. FeCl3 + H

2O(M:Neu.)

50. NO2 + S + H

2O(R: N from +5 to +4 and S from -2 to 0. Note that conc. HNO

3 is always

reduced to reddish brown gas NO2 and H

2S is always oxidised to S)

LEVEL - IISET-I:1. SO

2(R: show the changes in ON)

2. BaO+CO2(M)

3. PbO +SO2(R: S from -2 to +4 and O from 0 to -2, this is called the roasting of an ore)

4. PbCl2(s)+HNO

3(M/DR/preci.)

5. I2 + H

2O(R:I from -1 to 0 and O from -1 to -2)

6. NaNO2 + H

2O(M: N

2O

3 is the anhydride of HNO

2 and hence the nitrite salt is formed)

7. NaAlO2 + H

2O(M:Ampho.)

8. NaNO3 +H

2O(M/Neu.)

9. Zn + CO(R: Zn from +2 to 0 and C from 0 to +2)10. Ca(OH)

2(M)

11. BaSO4 + H

2O

2(M/DR)

12. Ti +MgCl2(R:Displ.)

13. Cr2(SO

4)

3+H

2O(M:Neu.)

14. Ba(CH3COO)

2 + H

2O(M/Neu.)

15. K2ZnO

2+H

2O(M:Ampho.)

16. K2SnO

3 +H

2(R:Ampho./Sn from 0 to +4 and H from +1 to 0)

17. PbO +O2(R:Pb from +4 to +2 and O from -2 to 0)

18. O2 +Br

2+H

2O(R: Br from -1 to 0 and O from 0 in O

3 to -2 in H

2O. Note that in all

reaction involving ozone, O2 is formed alongwith other products)


19. CuSO4 +SO

2+H

2O(R:Cu from 0 to +2 and S from +6 to +4. Note that conc. H

2SO

4

reacts with most metals to produce SO2)

20. Cu(NO3)

2+NO

2+H

2O(R: Cu from 0 to +2 and N from +5 to +4. Note that conc. HNO

3

reacts with most metals to produce the reddish brown NO2 gas)

21. SrSO4(s)+Ca(NO

3)

2(M:D.R/preci.)

22. Hg +H2O(R: Hg from +2 to 0 and H from 0 to +1)

23. NO2 + CO

2 +H

2O(R: N from +5 to +4 and C from 0 to +4).

24. K3PO

4 + H

2O(M:Neu./ P

2O

5 is the anhydride of H

3PO

4)

25. PbCl2 +Cl

2+H

2O(R:Pb from +4 to +2 and Cl from -1 to 0)

26. Mg3(PO

4)

2 +H

2O(M:Neu.)

27. PH3+Al(OH)

3(M:hydrolysis of phosphide salt)

28. Ca(OH)2 +C

2H

2(M:hydrolysis of carbide salt)

29. S +H2O(R: S goes from +4 to 0 and also S from -2 to 0)

30. SnCl4 + H

2O(M: Sn remains at +4)

31. Al2(SO

4)

3 +H

2S(M)

32. BaO2(R: O from -2 to -1 in peroxide and also O from 0 to -1)

33. Na2CO

3 +CO

2 +H

2O(M:thermal decomposition of bicarbonate)

34. KNO2 + O

2 (R: N from +5 to +3 and O from -2 to 0)

35. NH3 + Na

2CO

3 + H

2O(M)

36. N2O+2H

2O(R: N from -3 to +1 and N from +5 to +1)

37. NaAlO2 +H

2(R:Ampho.: Al from 0 to +3 and H from +1 to 0)

38. PbCl2+Cl

2+H

2O(R: Pb from+8/3 to +2 and Cl from -1 to 0. Note that Pb

3O

4 called the

red lead reacts in the same manner as PbO2)

39. PbBr2+H

2(R: displ.)

40. No reaction, Br2 is below Cl

2

41. Cr(OH)2(s)+NaNO

3(M/DR/preci)

42. HIO3(M: I

2O

5 is the anhydride of HIO

3)

43. MnS(s)+HCl(M:DR/preci)44. (NH

4)

2SO

4 (M: salt formation)

45. NO2 +S + H

2O(R: N from +5 to +4 and S from -2 to 0)

46. ZnSO4 +Cu(R:Displacement)

47. NH4Cl +N

2(N from -3 to 0 and Cl from 0 to -1. Note that due to excess of ammonia,

NH4Cl is formed by the reaction HCl with ammonia)

48. Fe3O

4(magnetic oxide)+H

2(R: Fe from 0 to +8/3 and H from +1 to 0)

49. HOCl or HClO(Cl2O is the anhydride of hypochlorous acid)

50. NaClO2 +H

2O(Cl

2O

3 is the anhydride of chlorous acid, HNO

2 from which chlorite salt

is produces in the above reaction).

SET-II The reader is advised to indicate the changes of ON in the following equations.1. NaNO

2 + NaNO

3 +H

2O(R: NO

2 is the mixed anhydride of HNO

2 and HNO

3)

2. FeCl3(R: syn.)


3. SnCl4 + NO

2 + H

2O(R)

4. Al(OH)3 + CH

4 (M)

5. HIO3 + NO

2 + H

2O (R)

6. HI + H3PO

3 (M)

7. N2O

5 + H

3PO

4(M: dehydration)

8. H2SO

4 + HCl(R)

9. KOH(M)10. I

2 + H

2O(R)

11. HClO4(M)

12. NaCl + NO + NO2 + H2O (R:Dispr.; N from +3 to +4 and +3 to +2. Note that when any

nitrite salt reacts with dilute acid, it gives HNO2 which gives NO and NO

2 and H

2O).

13. K2SO

4 + MnSO

4 + S + H

2O(R)

14. CO2 + H

2O (R: combustion)

15. Ag + Cu(NO3)

2(R: Metal displ.)

16. K2SO

3 + H

2O(M)

17. NaCl + SO2 + S + H

2O (R: note thiosulphate reacts with dilute acids to produce SO

2 gas

like sulphite salt and besides that sulphur is formed)18. Mg + Li

2O(R: Metal displ.)

19. K2SO

4 + Cr

2(SO

4)

3 + Fe

2(SO

4)

3 + H

2O(R)

20. NaCrO2 + H

2O(M: Ampho.)

21. Na2CrO

4 + H

2O(R: Cr from +3 to +6 and O from -1 to -2)

22. Na2SiO

3 + H

2(R: Ampho.)

23. I2 + SO

2 + H

2O(R)

24. K2PbO

2 + H

2(R: Ampho.)

25. Ag + NO2 + O

2(R: note that silver and mercuric nitrates decompose to their respective

metals alongwith NO2 and O

2)

26. H3PO

4 + NO

2 +H

2O(R)

27. No reaction: stable to heat28. K

2MnO

4 + MnO

2 + O

2(R: Mn from +7 to +6 and +4 while O from 0 to -2)

29. O2 + K

3[Fe(CN)

6] + KOH(R: Fe from +2 to +3 while O from 0 to -2)

30. Zn2[Fe(CN)

6] + K

2SO

4

31. Ca(OH)2 + H

2 (R: H:-1 to 0; H:+1 to 0)

32. CaH2(R: Synthesis)

33. Fe + H2O (R:Fe:+8/3 to 0; H:0 to +1)

34. H2SO

3 +2HCl (M)

35. H2O

2+BaCO

3 (M)

36. Al2O

3 + H

2O (M)

37. N2O + Cu ------>CuO + N

2 (R)

38. Cu2I

2 + I

2(R:Cu:+2 to +2; I:-1to 0)

39. HgCl + Ag(R: Displacement)40. Xe +HF(R: Xe:+4 to 0; H:0to +1)41. As

2O

3 + Ag + HNO

3 (R: Ag: +1 to 0; H: -1 to +1)


42. ZnO + SO2 +O

2 (R: S: +6 to +4; O:-2 to 0)

43. NaNO3+NH

3+H

2O(M)

44. NaAlO2 + NH

3 + H

2O(R: Al: 0 to +3; N:+3 to -3)

45. NH4Cl + NO + NO

2 +H

2O (R: dispropr.: N:+3 to +2; N:+3 to +4)

46. Fe3[Fe(CN)

6]

2 + K

2SO

4 (M)

47. K3[Fe(CN)

6] + KCl (R: Fe:+2 to +3; Cl:0 to -1)

48. K4[Fe(CN)

6] + K

2SO

4 (R: Fe: +3 to +2; S: +4 to +6)

49. Na2CrO

4 + H

2O (M)

50. 2K3[Cu(CN)

4] (M: Complexation reaction)

SET-III

1. Na2SO

4 +H

2O

2 (M) 2. NH

4HSO

4 + H

2O

2(M)

3. Fe2(SO

4)

3 + H

2O (R) 4. Ag +O

2 + H

2O (R)

5. O2 + 2HCl (R) 6. PbSO

4 + H

2O (R)

7. NaCl + Be(R) 8. Na3BO

3 + H

2 (R)

9. Na2SiO

3 + H

2 (R) 10. S + NaOH ------>Na

2S + Na

2S

2O

3 +H

2O(R)

11. K2ZnO

2 +H

2O(M) 12. Na

2CO

3 + H

2O (M)

13. NaCN + H2(R: C:0 to +2; H:+1 to 0) 14. NaOH + NH

3(M)

15. NaI + NaIO3 +H

2O(R: dispropr.) 16. NH

3 + Ca(OH)

2 (M)

17. Na2BeO

2 + H

2O (M) 18. CH

4 + Be(OH)

2 (M)

19. Ca(HCO3)

2 (M) 20. CaCO

3 + CO

2 + H

2O (M)

21. Mg(OH)2 + H

2 (R) 22. CaSO

4 + HF (M)

23. CH4 + Al(OH)

324. KBO

2 + H

2O (M)

25. Si(OH)4 + HCl (M) 26. H

3BO

3 + HF (M)

27. B2O

3 + H

2O (M) 28. B + K

2O (R: displacement)

29. K2HPO

3(M) 30. AlN + CO(R)

31. [Ag(NH3)

2]Cl(M: complexation)

32. K2ZnO

2 + NH

3 +H

2O(M: Zn: 0 to +2; N:+5 to -3)

33. No reaction(Al is above Fe) 34. Al2(SO

4)

3 + SO

2 + H

2O (R)

35. Al4C

3 +CO(R: disproprl) 36. CO

2 + NO

2 + H

2O (R)

37. 2CO (R) 38. Pb + CO (R)38. CO + CO

2 + H

2O (R:C:+3 to +2; C:+3 to +4: Dehydration)

40. CO + H2O (M: Dehydration) 41. Fe(CO)

5 (M: Complexation)

42. Fe + CO2(R) 43. I

2 + CO

2(R)

44. KHCO3(M) 45. K

2SiO

3 + H

2 (R)

46. MgO + Si(R)47. Sn(NO

3)

2 + NH

4NO

3 + H

2O(R) 48. 2SnCl

2 (R)

49. FeCl2 + SnCl

4 (R) 49. K

2SnO

2 + H

2O (M)

50. PbCl2 +Cl

2 + H

2O(R)

section-ii logic of inorganic reactions types of...

Documents