UNIT 4: Chemical Reactions – Stoichiometry and ThermodynamicsPart B: Chemical Reactions

Big Picture Ideas:1. The identity of the reactants helps scientists to predict the products in a chemical reaction.2. Quantitative relationships exist with all chemical reactions that allow scientists to predict amounts

of products formed, reactants consumed, and percent yield based on theoretical maximum.

Big Picture Question: How can you predict the products in a chemical reaction?

Suggested ResourcesHomework AssignmentsClasswork AssignmentsLaboratory ActivitiesFormative AssessmentsTextbook pages: Chapters 11 & 18Websites: www.webelements.com

Key Terms:1. chemical reaction2. chemical equation3. reactants4. yields5. products6. coefficient/mole7. subscript8. diatomic molecules9. synthesis/direct

combination10. decomposition11. single

replacement/displacement12. double replacement/displacement13. combustion14. activity series15. aqueous16. kinetics17. catalyst18. surface area

Directions: Use this information as a general reference tool to guide you through this unit. Don’t hesitate to ask your teacher for help!

By the conclusion of this unit, you should know the following:

1. There are five basic types of chemical reactions (S, D, SR, DR, Comb.) that exhibit distinct patterns for the prediction of products.

2. Experimental evidence can be used to identify products in a reaction.

3. All reactions follow the Law of Conservation of Matter (balancing equations).

4. Symbols are used to identify different aspects of a chemical reaction (states of matter, catalysts, heat, etc.).

5. Collision theory describes characteristics for a successful reaction.

6. Factors can be altered to affect the rate of a reaction (temperature, surface area, catalyst, concentration).

By the conclusion of this unit, you should be able to do the following:

1. Balance chemical reactions.2. Identify type of chemical reaction.3. Identify if a reaction will occur using an activity series.4. Predict products for a reaction.5. Write balance formula equation given chemical

equation (words).6. Using the collision theory, explain how altering the

temperature, surface area, concentration and the addition of a catalyst affects the rate of a reaction.

1. What type of reaction is it?a. element + element b. ionic compound + ionic compound c. element + ionic compound d. compound e. compound + oxygen

2. How can you tell if a chemical change has taken place? List examples.

3. Define a chemical reaction. Why must we balance chemical equations? (If it is a “must” there is a “law” governing the concept).

4. Balance each reaction below. Identify each type the following reactions are:a) NaOH (aq) + Pb(NO3)2 (aq) NaNO3 (aq) + Pb(OH)2 (s)b) CH4 (g) + O2 (g) CO2 (g) + H2O (l)c) Fe (s) + NaBr (aq) FeBr3 (aq) + Na (s)d) Pb (s) + O2 (g) PbO (g)e) Na2CO3 (s) Na2O (s) + CO2 (g)

5. Complete and balance each reaction below:a) Mg + HCl _________ + ____________b) C2H6 + O2 _________ + ____________c) CaF2 + Na2SO4 _________ + ____________d) Sr + N2 __________

6. List three factors affecting the rate of a chemical reaction. Know why they affect the reaction rate (collision theory!)

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NOTES: CHEMICAL REACTIONSVOCABULARY:

Products

Reactants

+

(s)

(l)

(g)

(aq)

Catalyst

Activation Energy (Ea)

Δ heat

Pt

ENERGY OF CHEMICAL REACTIONS:

Exothermic Reaction: ΔH is negative (–) Endothermic Reaction: ΔH is positive (+)(heat is a “product”) (heat is a “reactant”)

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KINETICS: RATE OF CHEMICAL REACTIONS

The rate of a reaction increases when the # of collisions increases.

Collision Theory:

What factors may cause the # of collisions to increase?

1. Temperature

2. Concentration of the reactants

3. Particle size (surface area) of the reactants4

Energy

Time

Energy

Time

4. Nature of the reactants

5. Adding a catalyst or inhibitor to the reaction

BALANCED CHEMICAL REACTIONS

Law of Conservation of Matter:

WORD FORMULA BALANCED EQUATIONS

1. word equation: hydrogen gas reacts with oxygen gas to form water

formula equation: _______________________________________________

diagram:

balanced reaction _______________________________________________

2. word equation: magnesium reacts with hydrochloric acid solution (HCl in water) to form magnesium chloride and hydrogen.

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formula equation: ____________________________________________________________

diagram:

balanced reaction _____________________________________________________________

Try balancing these chemical reactions:

a. Na + H2SO4 Na2SO4 + H2

b. K + Cl2 KCl

c. S8 + O2 SO2

d. F2 + FeBr3 FeF3 + Br2

e. H2SO4 + Al Al2(SO4)3 + H2

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f. C2H6 + O2 CO2 + H2O

g. NaNO3 + Ca(MnO4)2 NaMnO4 + Ca(NO3)2

h. P4 + KClO3 KCl + P2O5

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TYPES OF REACTIONS

There are Five Basic Reaction Types1. Synthesis (S)2. Decomposition (D)3. Single Replacement (SR)4. Double Replacement (DR)5. Combustion (C)

A. Synthesis1. Definition - two or more reactants join together to form one single product

2. General Form:A + B AB

3. Examples:a. 2 Na + Cl2 2 NaClb. 2 Mg + O2 2 MgOc. 4 Al + 3 O2 2 Al2O3

d. H2O + MgO Mg(OH)2

B. Decomposition1. Definition - one single reactant, a compound, breaks apart into two or more simpler products

2. General Form:AB A + B

3. Examples:a. 2 H2O 2 H2 + O2

b. 2 HgO 2 Hg + O2

c. 2 Ag2O 4 Ag + O2

d. CaCO3 CaO + CO2

C. Combustion Reactions1. Definition - oxygen reacts with another substance, often producing energy in the form of heat

and light

2. Types of Combustiona. Complete Combustion

(1) Definition - if sufficient oxygen is present to burn completely(2) Hydrocarbons combine with oxygen to produce carbon dioxide and water

3. General Form (Complete Combustion):CxHy(Oz) + O2 CO2 + H2O

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4. Examples:a. CH4 + 2 O2 CO2 + 2 H2Ob. C6H12O6 + 6 O2 6 CO2 + 6 H2Oc. 2 C4H10 + 13 O2 8 CO2 + 5 H2Od. C7H16 + 11 O2 7 CO2 + 8 H2O

D. Single Replacement1. Definition - atoms of one element replace the atoms of another element that is part of a

compound. In other words, an element + a compound yields a new element + a new compounda. If the atom of the single element is a metal, it replaces the metal in the compound

(**metals can also replace hydrogen)b. If the atom of the single element is a non-metal, it replaces the non-metal in the

compound

2. General Form:AX + B BX + A or AX + Y AY + Xwhere A, B are metals or hydrogen and X, Y are non-metals

3. Examplesa. Cu + AgNO3 Cu(NO3)2 + Agb. K + H+(OH-) KOH + H2

c. Zn + HCl ZnCl2 + H2 d. NaI + Cl2 NaCl + I2

e. KBr + F2 KF + Br2

4. Do these reactions occur?a. Zn + H2SO4 H2 + ZnSO4 (yes, Zn is more reactive than H)b. Sn + 2 HNaNO3 Sn(NO3)2 + 2 Na (no, Sn is less reactive than Na)c. 2 NaCl + F2 2 NaF + Cl2 (yes, F is more reactive than Cl)d. CaCl2 + I2 CaI2 + Cl2 (no, I is less reactive than Cl)

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E. Double Replacement1. Definition - an exchange of cations (+ ions) between two ionic compounds

2. General Form:AB + CD AD + CB

(***remember, these are ionic compounds and the cations (metals) must be written first. A and C are the cations)

3. Examples:a. NaOH + HCl NaCl + H+(OH-)b. BaCl2 + K2CO3 BaCO3 + 2 KClc. 3 KOH + H3PO4 3 H20 + K3PO4

d. Pb(NO3)2 + 2 KI 2 KNO3 + PbI2

4. The “driving forces” in double replacement reactions (one of these three things must be a product in order for these reactions to occur):

a. a liquid (like water) must form, orb. a solid (a precipitate) must form, orc. a gas must form

5. What is a precipitate?a. It is insoluble or slightly soluble in waterb. A solubility chart can help determine thisc. Are these soluble or insoluble?

(1) BaCl2 - soluble, so the reaction will not occur(2) AgCl - insoluble, so the reaction will occur(3) Ca3(PO4)2 - insoluble, so the reaction will occur(4) NaNO3 - soluble, so the reaction will not occur

6. Do these reactions occur?a. FeS (s) + HCl (aq) FeCl2 (aq) + H2S (g) ( yes, a gas is produced)b. Pb(NO3)2 (aq) + 2 KI (aq) 2 KNO3 (aq) + PbI2 (s) (yes, PbI2 is insoluble and thus a

precipitate)c. FeCl3 (aq) + Al(NO3)3 (aq) Fe(NO3)3 (aq) + AlCl3 (aq) (no, both products are

soluble, no other “driving force” is present)d. H2SO4 (aq) + 2 KOH (aq) K2SO4 (aq) + 2 H+(OH-) (l)

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SYNTHESIS, DECOMPOSITION AND COMBUSTION REACTIONS

Synthesis:

Decomposition:

Combustion of a hydrocarbon:

Practice:

Balance each reaction below. Then identify the reaction type.

a. H2 + Br2 HBr ________________________

b. C4H8 + O2 CO2 + H2O ________________________

c. NaOH Na2O + H2O ________________________

d. Ba(ClO3)2 BaCl2 + O2 ________________________

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First write and balance the equation. Then identify the reaction type.

e. phosphorus + oxygen tetraphosphorus decoxide ________________________

f. pentane (C5H12) + oxygen carbon dioxide + water ________________________

g. magnesium chlorate magnesium chloride + oxygen ________________________

h. when solid calcium carbonate is heated calcium oxide and carbon dioxide are formed

________________________

i. the formation of calcium nitride from calcium and nitrogen________________________

j. sulfur trioxide mixes with water in the atmosphere to form sulfuric acid________________________

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SINGLE DISPLACEMENT REACTIONS ANDDOUBLE DISPLACEMENT REACTIONS

1. Single Displacement Reactions (aqueous ONLY)metals:

standard:

example:

metal + acid:standard:

example:

metal + water:standard:

example:

halogens:standard:

example:

2. Double Displacement (aqueous only)standard:

example:

3. Identify the reaction type for each reaction below. Then complete and balance the reaction.

__________________________a. Ba + AgNO3 ___________________________

__________________________b. F2 + KI ______________________________

__________________________c. NaOH + CaCl2 ___________________________

__________________________d. Zn + H2SO4 ____________________________14

WRITING WORD EQUATIONS

_________________1. aluminum chlorate aluminum chloride + oxygen

_________________2. lithium + iron (III) nitrate lithium nitrate + iron

_________________3. magnesium carbonate magnesium oxide + carbon dioxide

_________________4. tin + nitrogen tin (IV) nitride

_________________5. zinc reacts with nitric acid to form zinc nitrate and hydrogen

_________________6. calcium hydroxide breaks down to form calcium oxide and water

WRITING WORD EQUATIONS WITH PREDICTING PRODUCTS

_________________1. aluminum + oxygen

_________________2. sodium + silver nitrate

_________________3. magnesium + hydrochloric acid

_________________4. solutions of iron (III) nitrate + potassium sulfate are mixed

_________________5. chlorine gas is bubbled through a solution of lithium iodide

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Fun With Predicting Reaction Products

Predict the products of each of the following chemical reactions. If a reaction will not occur, explain why not:

1) ____ Ag2SO4 + ____ NaNO3

2) ____ NaI + ____ CaSO4

3) ____ HNO3 + ____ Ca(OH)2

4) ____ Zn + _____ HNO3

5) ____ AlCl3 + ____ (NH4)PO4

6) ____ Pb + ____ Fe(NO3)3

7) ____ C3H6 + ____ O2

8) ____ Na + ____ CaSO4

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WRITING WORD EQUATIONS

a. lithium + nitrogen lithium nitride

b. aluminum + oxygen aluminum oxide

c. sodium carbonate sodium oxide + carbon dioxide

d. zinc + phosphoric acid zinc phosphate + hydrogen gas

e. chlorine gas + lithium iodide lithium chloride + iodine

f. sodium hydroxide sodium oxide + water

g. magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas

h. solutions of iron (III) chloride and sodium hydroxide react to form iron (III) hydroxide and sodium chloride

i. when sodium is added to water, sodium hydroxide and hydrogen gas are produced

j. when zinc is placed in a solution of lead (II) nitrate, zinc nitrate and solid lead metal are formed

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HOMEWORK: BALANCING CHEMICAL REACTIONS NAME:

1. ___P4 + ___O2 ___P2O5

2. ___Al + ___HCl ___AlCl3 + ___H2

3. ___Al2(SO4)3 + ___Ca(OH)2 ___Al(OH)3 + ___CaSO4

4. ___H2S + ___Cl2 ___S8 + ___HCl

5. ____Mg + ____N2 ____Mg3N2

6. ____Fe + ____H2O ____Fe3O4 + ____H2

7. ____NaOH + ____Cl2 ____NaCl + ____NaClO + ____H2O

8. ____C4H10 + ____O2 ____CO2 + ____H2O

9. _____CH3OH + _____O2 ____CO2 + _____ H2O

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HOMEWORK: SYNTHESIS, DECOMPOSITION AND COMBUSTION REACTIONS

1. Classify each equation below as synthesis, decomposition or combustion. Then balance each equation.

________________________ 1. NaClO3 NaCl + O2

________________________ 2. Cu + S Cu2S

________________________ 3. S + O2 SO3

________________________ 4. C3H6 + O2 CO2 + H2O

2. Classify each equation below as synthesis, decomposition or combustion. Write and balance the equation for the reaction.

________________________ 1. potassium hydroxide potassium oxide + hydrogen

________________________ 2. dicarbon tetrahydride + oxygen carbon dioxide + water

________________________ 3. lithium chlorate lithium chloride + oxygen

________________________ 4. magnesium + nitrogen magnesium nitride

________________________ 5. aluminum burns in pure oxygen to form aluminum oxide

________________________ 6. sodium carbonate is heated to form sodium oxide and carbon dioxide

________________________ 7. water and dinitrogen pentoxide combine to form nitric acid

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CLASSIFICATION OF CHEMICAL REACTIONS

Classify the reactions below as synthesis, decomposition, single replacement or double replacement:

1. 2 H2 + O2 2 H2O __________________________

2. 2 H2O 2 H2 + O2 __________________________

3. Zn + H2SO4 ZnSO4 + H2 __________________________

4. 2 CO + O2 2 CO2 __________________________

5. 2 HgO 2 Hg + O2 __________________________

6. 2 KBr + Cl2 2 KCl + Br2 __________________________

7. CaO + H2O Ca(OH)2 __________________________

8. AgNO3 + NaCl AgCl + NaNO3 __________________________

9. 2 H2O2 2 H2O + O2 __________________________

10. Ca(OH)2 + H2SO4 CaSO4 + 2 H2O __________________________

11. Copper metal is put into a solution of silver nitrate. Solid silver precipitates, and copper (II) nitrate solution is formed.

___________________________

12. Methane gas burns in pure oxygen to give carbon dioxide and water

___________________________

13. When sodium carbonate is heated, it breaks down to form sodium oxide and carbon dioxide.

___________________________

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HOMEWORK – PRACTICE REACTION WRITING

Identify the reaction type (synthesis, decomposition, combustion, single displacement, double displacement) for each reaction written below. Then write the balanced equation for each reaction.

_______________________ 1. Magnesium is placed in a solution of aluminum nitrate

_______________________ 2. Calcium burns in pure oxygen

________________________ 3. The combustion of propane (C3H8)

__________________________________________________________________________________

________________________ 4. Fluorine is bubble through a solution of sodium bromide

_________________________________________________________________________________

_______________________ 5. Solutions of potassium chloride and barium hydroxide are mixed

__________________________________________________________________________________

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