chemistry : notes form 4
TRANSCRIPT
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Chemistry and Its Importance
Chemistry – earlier study of alchemy (an art
of transforming common metals to precious
metals, usually lead to gold but to no success)
(alchemy has since been proven to be a
wrong and currently dead branch of science)
Chemistry – is the study of
the composition, structure, properties and int
eractions of matter.
Founder of Modern Chemistry (try and
read up on the history of these two great
men)
1. Robert Boyle (1627-1691) –
performed controlled eperiments and
published his !or" !ith elaborate details
such as procedure, apparatus and
obser#ations.
2. Antoine Lavoisier (17$%-179$) –
de#eloped the &a! of 'onser#ation of
ass and thetheory of combustion.
Scientific Method
1. a"ing bser#ation
2. a"ing *nference (smart guess)
%. *dentifying the +roblem
$. a"ing a ypothesis
. *dentifying the ariables
6. 'ontrolling the ariables
7. +lanning an /periment
0. 'ollecting ata9. *nterpreting ata
1. a"ing a 'onclusion
11. 3riting a 4eport
SM Form ! " #erminolo$y and
Concepts% #he Structure of the Atom
Important #erms
Matter – anything that occupies space and
has mass.
Compound – a substance
consists t!o or more elements that
are chemically bonded (molecule or ions).&lement – a substance that cannot be made
into anything simpler by chemical reaction.
Atom – smallest particle of an element.
Molecule – a group of t!o or more atoms.
Ion –
a positi#ely charged 5 negati#ely charged
particle.
Cations – positi#ely-charge ions. /ample
, 8 , $ and g2
Anions – negati#ely-charge ions. /ample
:r-, -, 2- and ;2%2-
'elocity of the particle increases !hen
ing 5 ;olidification – li?uid -@
solid
2. elting – solid -@ li?uid
%. /#aporation – li?uid -@ gas 5 #apour
$. 'ondensation – gas 5 #apour -@ li?uid
. ;ublimation – gas 5 #apour -@ solid
6. ;ublimation – solid -@ gas 5 #apour
( Sublimation – iodine, ammonium chloride
and solid carbon dioxide)
Important Scientist and #heir
Contributions
:erry :erry
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1. Atoms – consists of a positi#ely-
charged nucleus !ith a cloud of electrons
surrounding nucleus.
2. +rotons – positi#ely-charged particles.
0iels Bohr (*.*1)
1. /lectrons – surrounding the nucleus
(orbit).
ames Cad2ic3 (*.14)
1. eutrons – electrically neutral
subatomic particles.
2. eutrons – mass almost the same !ith
a proton.
%. ucleus of an atom – consists of
protons and neutrons.
Concepts of the Atomic Model
Modern Atomic Model
1. ucleus of an atom – consists
of protons and neutrons.
2. /lectrons – mo#ing around
the nucleus (orbits 5 electron shells5
?uantum shells)
roton number 5 Atomic number 5
0umber of protons
1. umber of protons in its atom.
2. umber of electrons (neutral atom).
0ucleon number 5 Mass number 5
0umber of nucleon1. ;um of the number protons and
neutrons.
Isotopes – atoms of the same element
!ith same proton number but different
nucleonnumbers.
SM Form ! " #erminolo$y and
Concepts% Chemical Formulae and
&6uations " art *
1. Relative atomic mass, Ar is the atomic
mass of an atom !hen compared toa standard atom
2. Standard atom
7ydro$en scale hydrogen is the lightest
atom of all and the mass of one hydrogen
atom !as assigned 1 unit.
3ea"ness of ydrogen scale
not too many elements can
react readily !ith hydrogen,
the reacti#e masses of some elements
!ere not accurate,
hydrogen eists as a gas at room
temperature and has a number of isotopes !ith
different masses.
7elium scale the second lightest atom of all
and the mass of one helium atom !as
assigned 1 unit.
3ea"ness of elium scale
ass of 1 helium atom B $ times the
mass of a hydrogen atom
;o, mass of 1 helium atom B $ times
1512 mass of a carbon atom helium eists as a gas at room
temperature and
helium is an inert gas.
89y$en scale chose as the standard atom to
compare the masses of atoms
3ea"ness of ygen scale
the eistence of three isotopes of
oygen !ere disco#ered,
natural oygen (containing all thethree isotopes) as the standard ('hemist)
and
used the isotopes oygen-16 as the
standard (+hysicists).
Carbon scale standard atom of
comparison internationally.
a carbon-12 atom is 12 times
hea#ier than an atom of hydrogen,
used as the reference standard in mass
spectrometers,
eists as a solid at room temperature, most abundant carbon isotope,
happening about 90.09C and
carbon-12 is close to the agreement
based on oygen.
%. Relative molecular mass, Mr of a
substances is the a#erage mass of
a molecule (t!o or more atoms) of the
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substances !hen compared 1512 !ith of the
mass of a carbon-12 atom.
$. Relative formula mass: Fr is
for ionic compound !hich is calculated by
adding up therelati#e atomic masses of all the
atoms.
. &9ample
4elati#e atomic mass, Ar of helium B $
4elati#e molecular mass, r of '2 B
12 2(16) B $$
4elati#e formula mass, =r of a'l B
2% %. B 0.
4elati#e formula mass, a2'%D12
B 2(2%) 12 %(16) 1 E2(1) 16F B 206
*talian physicist Amedeo Avogadro (ame
at birth &oren>o 4omano Amedeo 'arlo
A#ogadro) Born% 9 August 1776
Birthplace%
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moles of atoms of each element in a
compound.
2. olecular formula B (empirical formula)nn is a positi#e number
'ompound olecular formula n /mpirical formula
'arbon dioide '2 1 ('/thane '% 2 ('
+ropene '2 % ('
Llucose '2 6 ('
Muinine '112 2 '
%. 'hemical formulae for co#alent compounds.
ame 'hemical
formula
umber of each element
itrogen gas 2 2 nitrogen atoms
ygen gas 2 2 oygen atoms Ammonia % 1 nitrogen atom and %
hydrogen atoms
3ater 2 2 hydrogen atoms and 1
oygen atom
$. 'ations are positi#ely-charged ions.
'harge 'ations =ormula
1 Ammonium ion $
1 N 'opper(*) ion 'u
1 ydrogen ion
1 &ithium ion &i
1 N ic"el(*) ion i
1 +otassium ion 8
1 ;il#er ion Ag
1 ;odium ion a
2 :arium ion :a2
2 'alcium ion 'a2
2 N 'opper(**) ion 'u2
2 N *ron(**) ion =e2
2 N &ead(**) ion +b2
2 agnesium ion g2
2 N anganese(**) ion n2
2 ic"el(**) ion i2
2 N
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ono- 1
i- 2
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eedelee#Hs +eriodic
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+oor conductors of heat
elting point and boiling point
increases (going do!n the group) –
atomic si>e increases and force of
attraction bet!een atoms of each element
become stronger ensity of element increases (going
do!n the group)
'hemical properties
'hemically inert 5 not reacti#e 5 non-
flammable – do not gain, lose or share
electrons !ith other elements
Pses
elium – airships, !eather balloons,
cool do!n metals
eon – ad#ertising light bulb
Argon – !elding, filled light bulbs
8rypton – used in laser, filled
photographic flash lamps
4adon – treat cancer
(#ips Please follow the safety precaution
prescribed by your teacher in handling the
alkali metals "if you were given the chance to
do so#. The reason is simple, as you will only
need to see the volatile nature of alkali metals
here when they are in contact with water,
!rainiacs video on $lkali %etal &view here'.
$fter viewing the video, you should have noreasons to not follow the safety precautions#
(Second #ips Do try your best to memorise
the elements down the group. (ead aloud
everyday a few times) &ithium, ;odium,
+otassium, 4ubidium, 'aesium and
=rancium. *f you do so, youll memorise it
without much effort. Thatll be an advantage
in exams.#
SM Chemistry Form ! 0otes "
eriodic #able of &lements (art 1)
Alkali metal atom arrangement
=roup * elements
Lroup 1 elements are "no!n as al"ali
metals
Atomic radius (atomic si>e)
– increases (going do!n the group)
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atomic si>e increases and number of shells
occupied !ith electrons increases 5
metallic bonding bet!een atoms becomes
!ea"er Q less heat energy is re?uired to
o#ercome the !ea"er metallic bonding.
&o! density (&i, a and 8 float on the
surface !ater 5 4b, 's and =r sin" in the
!ater)
ensity of element increases (going
do!n the group)
'hemical properties
'hemically #ery reacti#e and react
rapidly !ith oygen and !ater #apour in
the air (must be "ept in paraffin oil)
4eacti#ity increases (do!n the group)
– ho! easily it can lose one (single)
its #alence electronto achie#e stable (octetor duplet) electron arrangement
4eact #igorously !ith cold !ater –
produce al"aline metal hydroide
solutions and hydrogen gas
4eact !ith oygen – produce !hite
solid metal oides and metal oides can
dissol#e in !ater to form al"aline metal
hydroide solutions
4eact !ith halogens – produce !hite
solid metal halides
;afety precautions 'annot hold !ith bare hands
3ear safety goggles and glo#es
o flammable substance nearby
A#oid the fire
(#ips +ou should draw out the diatomic
molecules and their electron configurations
so that you can better understand why they
typically exist in the form of diatomic
molecules. Try to also memorise the atomic
sie as they go down a group. -ote whether if
it is metallic or nonmetallic. /ow abouttheir oxidising abilities0 *f you can answer
those and beyond, you would have mastered
the basic knowledge on halogens.#
SM Chemistry Form ! 0otes "
eriodic #able of &lements (art !)
Molecules of Halogen
=roup */ elements
Lroup 17 elements are "no!n
as halogens
/ist as diatomic molecules (=2, 'l2,
:r2, *2 and At2)
on-metals
Atomic radius (atomic si>e)
– increases (going do!n the group)
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elting point and boiling point
increases (going do!n the group) –
molecular si>e increases 5 forces of
attraction bet!een molecules become
stronger Q more heat energy is re?uired to
o#ercome the stronger forces of attraction(an der 3aalsH forces of attraction
bet!een molecules).
'olour =2 (pale yello2 $as),
'l2 ($reenish>yello2 $as),
:r2 (reddish>bro2n li6uid),
*2 (purplish>blac3 solid) and
At2 ( blac3 solid – rarest naturally
occurring element and etremely
radioacti#e)
&o! density
ensity of element increases (goingdo!n the group) – increase in atomic
mass
'hemical properties
'hemically reacti#e
4eacti#ity decreases (do!n the group)
– ho! easily it can gain one (single)
more #alenceelectron to achie#e
stable (octet) electron arrangement
4eact !ith !ater – produce t!o acids
4eact !ith hot iron – produce bro!n
solids iron(***) halides 4eact !ith sodium hydroide a
solution – produce !ater and t!o types of
sodium salts (sodium halide and sodium
halite(*))
;afety precautions
+oisonous gas
3ear safety goggles and glo#es
andle in the fume cupboard
SM Chemistry Form ! 0otes "
eriodic #able of &lements (art ?)
Elements: Zinc Copper Lead Magnesium
&lements in a period
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a, g, Al (metals) good conductor 5
;i (semi-metal) !ea" conductor of
electricity 5 +, ;, 'l (non-metals) cannot
conduct electricity
a, g (metals) form oides !ith
basic properties Al (metal) form oides !ith both
basic and acidic properties B amphoteric
oides
;i (semi-metal) forms oides !ith
acidic properties
+, ;, 'l (non-metals) forms oides
!ith acidic properties
Pses of semi-metals (metalloids)
;emiconductor (flo! in one direction)
icrochip
inc !ith dilute sulphuric acid to liberatehydrogen gas, man$anese(I') o9ide –
decomposition of hydrogen peroide to
liberate oygen gas, iron – aber
process, vanadium(') o9ide – 'ontact
process, platinum – st!ald process)
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=orm comple ions (bigger-si>ed
polyatomic ion) (eacyanoferrate(***)
ion 5 E=e(')6F%- )
Pses
*ron – used as steel
'hromium – coating corroded metals,heat-resisting alloys and ma"e stainless
steel
'opper – ma"ing cables, pipes and
electrical !ires
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Metal 0on>metal –@ Ionic compound
;odium bromine –@ ;odium bromide
'alcium chlorine –@ 'alcium chloride
&ithium oygen –@ &ithium oide
Aluminium nitrogen –@ Aluminium nitride
MetalsLroup 1
A lithium atom !ith an electron
arrangement of 2.1 achie#es stability after
it donates one #alence electron to form a
lithium ion, &i.
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of the fluoride ion, = -, is 2.0 !ith stable
octet electron arrangement.
A chlorine atom !ith an electron
arrangement of 2.0.7 achie#es stability
after it accepts one #alence electron to
form a chloride ion, 'l
-
.
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Covalent Bonds
*t is a chemical bond formed from
the sharing of #alence electrons bet!een
non-metal atoms to achie#e the stable
duplet of octet electron arrangement.
/ach shared pair of electrons isas one co#alent bond.
*t produces molecules.
Psually the co#alent bonds form
bet!een non-metal atoms from Lroup 1,
16 and 17 and sometimes can be formed
from Lroup 1$ (carbon and silicon) and
hydrogen.
'o#alent bond can be formed from
atoms of the same element and atoms of
different elements.
/ample
0on>metal 0on>metal –@ Covalent compound
:romine bromine –@ :romine (:r2)
itrogen nitrogen –@ itrogen (2)
'arbon chlorine –@
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of the follo!ing is the formula of the
compound formed bet!een O and RK
(A) R $O
(B) R 2O
(C) RO() RO2;olution
O has 6 #alence electrons, it needs to
share 2 electrons to achie#e the stable
octet electron arrangement.
R has $ #alence electrons, it needs to
share $ electrons to achie#e the stable
octet electron arrangement.
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1ovalent 1ompound
'o#alent 'ompound – co#alent bonding is
strong bonding bet!een the atoms in the
molecule
Ionic Compound ifferences Covalent Compound
*ons articles olecules
&ost or gained &lectron ;hared
;trong electrostatics
forces (*onic bond)
bet!een theoppositely-charged
ions arranged in a
%- giant crystal
lattice
Forces ;trong ('o#alent bond)
bet!een the atoms in the
molecule. 3ea" forces ofattraction bet!een the
molecules (#an der 3aalsH
forces)
;olid State Lases or #olatile li?uids
igh Meltin$ point &o! (;imple molecules)igh
(Liant molecules)
igh Meltin$ point &o! (;imple molecules)igh
(Liant molecules)
on-#olatile 'olatility ery #olatile (;imple
molecules)on-#olatile (Liant
molecules)
issol#e in !ater
and polar sol#ents
Solubility in
2ater
o not dissol#e in !ater
o not dissol#e in
organic sol#ent
Solubility in
or$anic solvent
issol#e in organic sol#ent
(ether, alcohol, ben>ene,
tetrachloromethane and
propanone)
'onduct electricity
in li?uid and
a?ueous solution
(positi#e and
negati#e ions canmo#e freely).
'annot conduct
electricity in solid
state (fied position
and cannot mo#e
freely).
&lectricity
conductor
'annot cond
any state (no
ses of covalent compounds as solvent
/ther – sol#ents in the etraction of
chemicals from a?ueous solution
Alcohol – sol#ents used to ma"e in"
and dye because these sol#ent are #olatile
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/ample for electrolytes (al"alis, acids, salt
solution or molten salt)
molten lead(**) chloride
copper(**) sulphate solution
solution containing ions such ashydrochloride acid
0on>electrolyte
on-electrolytes are molecules
that cannot conduct electricity and !ill
not undergo any chemical changes.
*t cannot conduct electricity due to
the absent of free mo#ing ions.
/ample of non-electrolytes (co#alent
substances)
molten acetone
molten naphthalene
glucose solution
Conductor
'onductors are substances that can
conduct electricity in solid or molten state
but do not undergo any chemical changes.
*t can conduct electricity due to
the flo! of electrons.
/ample of conductor
iron
graphite
mercury
Ionic Compounds
Solid state Molten state or a6ueous
state (dissolved in 2ater)
o not conduct electricity 'an conduct electricity
*ons are held in a lattice -
*ons do not mo#e freely *ons are free to mo#e
Covalent CompoundsSolid state Molten state or a6ueous
state (dissolved in 2ater)
o not conduct electricity o not conduct electricity
/ist in molecules /ist in molecules
olecules do not ha#e free
mo#ing ions
/ception 'l and
as free mo#ing ions in !ater
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Inert
electrodes
/lectrodes that do not ta"e
part in chemical reactions
during electrolysis
'arbon or
platinum
Active
electrodes
/lectrodes that ta"e part in
chemical reactions during
electrolysis
'opper or >inc
/ample 1
olten magnesium oide, g
*ons agnesium ions (g2) Q oide
ions (2-)
'athode (egati#e electrode)
g2 mo#e to the cathode
Anode (+ositi#e electrode) 2- mo#e
to the anode
/lectrons flo! from anode to the
cathode through the !ire
'an conduct electricity
/ample 2
olten lead(**) bromide, +b:r2
*ons &ead(**) ions (+b2) Q bromide
ions (:r - )
'athode (egati#e electrode)
+b2 mo#e to the cathode
Anode (+ositi#e electrode) :r - mo#e
to the anode
/lectrons flo! from anode to thecathode through the !ire
'an conduct electricity
/ample %
olten naphthalene
*ons o ions present (naphthalene is
co#alent compound !hich consists of
molecules B uncharged particles)
o electrons flo!s
'annot conduct electricity
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Anode (positi#e electrode) - mo#e
to the anode (ions are selecti#ely
discharge)
/ample 2
.1 mol dm% of copper(**) sulphate,
'u;$ solution +ositi#e ions (cations) copper ions
('u2) and hydrogen ions (),
egati#e ions (anions) sulphate ions
(;$2-) and hydroide ions (-)
'athode (negati#e electrode)
'u2 mo#e to the cathode (ions are
selecti#ely discharge)
Anode (positi#e electrode) - mo#e
to the anode (ions are selecti#ely
discharge)
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+ositi#e ions (cations) copper ions
('u2) and hydrogen ions (),
egati#e ions (anions) sulphate ions
(;$2-) and hydroide ions (-)
'athode (negati#e electrode)
'u2
mo#e to the cathode (ions areselecti#ely discharge). A bro!n deposited
on the cathode.
Anode (positi#e electrode) - mo#e
to the anode (ions are selecti#ely
discharge). Las bubbles are produced. A
colourless gas liberates and it ignites the
glo!ing !ooden splinter.
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*mportance of electroplating is to
pre#ent corrosion and impro#e the
appearance.
'athode obTect to be electroplated
Anode pure plating metal
/lectrolyte a?ueous solution containsplating metal ions
'oltaic Cell 5 =alvanic cell
*t is an electrochemical cell !hich con#erts
chemical energy –@ electrical energy
egati#e terminal more
electropositi#e (higher position in the
electrochemical series)
+ositi#e terminal less electropositi#e
(lo!er position in the electrochemical
series) /lectrons released (more
electropositi#e metal) through the !ire to
a less electropositi#e metal.
/ample 1 Iinc plate and iron plate are
placed in 1. mol dm% of lead(**) nitrate,
+b(%)2solution
egati#e terminal (Anode) Iinc metal
(Iinc plate dissol#es to form In2)
+ositi#e terminal ('athode) *ron
metal (hydrogen ions !ill be selecti#ely
discharge to form hydrogen gas. *t is
because is lo!er position than +b2 and
In2 in the electrochemical series)
/ample 2 agnesium plate and copper plate
are placed in 1. mol dm% of sodium chloride,
a'l solution
egati#e terminal (Anode)
agnesium metal (agnesium plate
dissol#es to form g2)
+ositi#e terminal ('athode) 'opper
metal (hydrogen ions !ill be selecti#ely
discharge to form hydrogen gas. *t is
because is lo!er position than
g2 and a in the electrochemical
series)
aniell Cell
*t is another eample of a #oltaic cell.
;olutions are connected by a salt
bridge (inert electrolyte) or a porous pot.
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'athode 'u2 2e –@ 'u (2)
#erall 2'u2 $- –@ 2'u 22
2.
Comparison of &lectrolytic Cells and 'oltaic Cells
;imilarities
/lectrons flo! through the eternal
circuit (connecting !ires)
Anode (oidation) loss of electrons
'athode (reduction) gain of electrons
ifferences
&lectrolytic Cell
Main basic
structures
A battery is needed to
supply electrical energy
&ner$y conversion /lectrical energy –@
chemical energy
#ransfer of electrons
at the positive
terminal
Anode (positi#e
terminal) idation –
anions lose electrons at
the anode
#ransfer of electrons
at the ne$ative
terminal
'athode (negati#e
terminal) 4eduction –
cations accept electrons
from the cathode
&lectrochemistry
*t is an arrangement of elements
according to their tendencies to donate
electrons to form cations.
igher position in the series B a metal
that has a higher tendencies to ionise and
form positi#e ions.
/lectrochemistry is constructed by
the potential difference (#oltage
difference) bet!een pairs of metals and
the ability of a metal to displace another
metal from its o!n salt solution.
A) &lectrochemical Series based on the
otential ifference ('olta$e
ifference)
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/tract useful metals (aluminium,
sodium and magnesium) from its ore
using electrolysis.
anufacture of useful chemical
substances (chlorine and sodium
hydroide) using electrolysis. /lectroplating of iron !ith chromium
to protect the iron layer.
;il#er-plating to ma"e fine cutleries.
oltaic cell (batteries)
/ffect of /lectrochemical *ndustries to!ards
the /n#ironment
ea#y metals (chromium and
mercury) – cause !ater pollution.
'hlorine gas is a toic gas – cause
problem (irritates) to human respiratory
system.
ercury cell (batteries) is highly toic.
*mproper disposal of industrial !aste
– cause !ater pollution.
'hapter 7 acid n basses Acids
An acid is a chemical substance
!hich ionises in !ater to
produce hydrogen ions, 5hydroonium
ions, %
. (a?) 2(l) –@ %
(a?)
/ample 'l(g) 2(l) –@ %
(a?) 'l -(a?)
Acid Acid name Ions
'l ydrochloric acid , 'l -
% itric acid , %-
2;$ ;ulphuric acid , ;$
2-
'%' /thanoic acid , '%'
-
Monoprotic acid B acid can produce
only one hydrogen ion per molecule in !ater. (/ample 'l)
iprotic acid B acid can produce t!o
hydrogen ions per molecule in !ater.
(/ample 2;$)
#riprotic acid B acid can
produce three hydrogen ions per molecule
in !ater. (/ample %+$)
Sodium hydroxide
Bases 5 Al3alis
A base is a chemical substance
!hich reacts !ith an acid to produce
a salt and !ater only.
:ase(s) acid(a?) –@ salt !ater (l).
/ample a(s) 'l(a?) –@
a'l(a?) 2(l)
:ase =ormula ;olubility in !
'opper(**) oide 'u *nsoluble bas
&ead(**) oide +b *nsoluble bas
agnesium oide g *nsoluble bas
Iinc hydroide In()2 *nsoluble bas
Aluminium hydroide Al()% *nsoluble bas
;odium oide a2 ;oluble base
'alcium oide 'a ;oluble base
;odium hydroide a ;oluble base +otassium hydroide 8 ;oluble base
:arium hydroide :a()2 ;oluble base
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etching and dissolution of metals
(purification and etraction of gold)
Sulphuric acid ardous al"ali to neutralise
acidic !aste!ater.
SM Chemistry Form ! 0otes " Acids
and Bases (art 1)
Chemical roperties
important efinition for Acids
onoprotic acid (monobasic acid) is an acid
!hich produce one mole of ion !hen one
mole of the acid ionise in !ater.
Monoprotic
acid
Monoprotic acid
name
'l ydrochloric acid
% itric acid
'%' /thanoic acid
.
olyprotic acids
iprotic acid (dibasic acid) is an acid !hich
produce t!o moles of ios from one mole of
the acid in !ater.
iprotic acid iprotic acid name
2;$ ;ulphuric acid
2'% 'arbonic acid
2'r$ 'hromic acid
2'2$ /thanedioic acid 5
alate acid
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SM Chemistry Form ! 0otes " Acids
and Bases (art ?)
(The above image is 4ust a representation,
colours may vary, so please follow the
colours described in the table below)
#he p7 scale and the Measurement of
p7 'alue of a Solution
p scale is a set of numbers used torepresent the degree of acidity or
al"alinity of a solution.
p is a measurement of the
concentration of hydrogen ions () in the
solution.
p #alue greater than 7 al"aline
solution
p #alue of eactly 7 neutral solution
p #alue less than 7 acidic solution
*n an acidic solution B higher in the
concentration of the ions, the lo!er thep #alue.
*n an al"aline solution B lo!er in the
concentration of the ions, the higher
the p #alue.
p solution can be measured by using
uni#ersal indicator, p paper and p
meter.
p7 value Colour of niversal
Indicator, 1, 2 4ed
% range red
$ range
range yello!
6 Rello!
7 Lreen
0 Lreenish-blue
9 :lue
1 :lue
11 :luish-purple
12, 1%, 1$ +urple
Stron$ Acids
;trength of an acid –
the degree of ionisation or dissociation of
the acid in !ater.
;trong acid – an acid !hich ionises 5
dissociates completely in !ater to
form high concentration of hydrogen
ions ().
/ample of strong acid ineral acid –
hydrochloric acid ('l), nitric acid(%) and sulphuric acid (2;$).
/ample of the strong acid reaction in
!ater 'l(a?) –@ (a?) 'l-(a?) (
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Stron$ Al3alis
;trength of an al"ali –
the degree of ionisation or dissociation of
the al"ali in !ater.
;trong al"ali – an al"ali
!hich ionises 5 dissociatescompletely in !ater to form high
concentration of hydroide ions ( – ).
/ample of strong al"ali ;odium
hydroide (a) solution, potassium
hydroide (8) solution and barium
hydroide (:a()2) solution.
/ample of the strong al"ali reaction
in !ater a(a?) –@ a(a?) -(a?)
Eea3 Al3alis
3ea" al"ali – an al"ali !hich ionises 5
dissociates partially in !ater to form lo!concentrationof hydroide ions ( – ).
/ample of !ea" al"ali ammonia
(%) solution.
/ample of the !ea" al"ali reaction in
!ater %(g) 2(l) VW-@ $(a?)
- (a?)
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acid of different concentration is added
and (iii) an al"ali is added.
0eutralisation
eutralisation B a reaction bet!een
an acid and a base5al"ali to
produce salt and !ater only. Acid al"ali –@ salt !ater
*onic e?uation of neutralisation
(a?) -(a?) –@ 2(l)
Application of 0eutralisation Reactions
in aily Life
igesti#e Tuices in
stomach
:rea" up food (only in acidic condition) and
maintained at p of bet!een
*nsect stings :ees and ants inTect an acidic li?uid into the
s"in but !asps inTect an al"aline li?uid.
base #itration
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