UNIT 4: Chemical Reactions – Stoichiometry and ThermodynamicsPart A: 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 Resources…Homework AssignmentsClasswork Assignments Laboratory ActivitiesFormative AssessmentsTextbook pages: Chapter 9Websites: www.webelements.com

Key Terms:1. chemical reaction2. chemical equation 3. 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

http://www.sciencelearn.org.nz/contexts/nanoscience/sci_media/images/chemical_reactions_involve_making_new_combinations ©2007-2009 The University of Waikato

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 must be 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 effecting the rate of a chemical reaction. Know why they effect the reaction rate (collision theory!)

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NOTES: CHEMICAL REACTIONS VOCABULARY:

Products what is formed in a chemical reaction; right of arrow

Reactants what goes into a chemical reaction; left of arrow

yields

+ and

(s) solid

(l) liquid

(g) gas

(aq) aqueous – only works when dissolved in water

Catalyst a substance that speeds up a reaction but is not itself consumed; provides an easier reaction pathway that requires less activation energy

Activation Energy (Ea) energy necessary to initiate a chemical reaction

ENERGY OF CHEMICAL REACTIONS:

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

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KINETICS: RATE OF CHEMICAL REACTIONS

Collision Theory: for a reaction to occur, the reactants must collide with sufficient energy and with the proper orientation (and in the correct ratio)

Factors Affecting Reaction Rate:

1. Temperature

if temperature is increased, the reaction will be quicker. faster moving particles collide more often, and more particles will have enough energy (Ea) when they collide

2. Particle size (surface area)

more exposed particles causes more collisions, so there will be more collisions with the correct orientation

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Energy

Time

Energy

Time

3. Nature of Reaction

reaction rate is also determined by the properties of the reactants

4. Adding a Catalyst or Inhibitor

a catalyst speeds up a reaction by lowering the required activation energyan inhibitor slows down a reaction by raising the activation energy

BALANCED CHEMICAL REACTIONS

Law of Conservation of Matter: matter cannot be created or destroyed in a chemical reaction

WORD FORMULA BALANCED EQUATIONS

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

formula equation: ____ H2 + O2 H2O ___________________________________________

diagram: H – H + O = O O + OH – H H H H H

balanced reaction ____2 H2 + O2 2 H2O ___________________________________________

2. word equation: Magnesium reacts with hydrochloric acid solution (HCl in water) to form

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magnesium chloride and hydrogen.

Formula equation: ____ Mg + HCl MgCl2 + H2 __________________________________

diagram: Mg + H – Cl Mg+2Cl-1 + H – H H – Cl

balanced reaction _______ Mg + 2 HCl MgCl2 + H2 ________________________________

Try balancing these chemical reactions:

a. 2Na + H2SO4 Na2SO4 + H2

b. 2 K + Cl2 2 KCl

c. S8 + 8 O2 8SO2

d. 3F2 + 2 FeBr3 2 FeF3 + 3Br2

e. 3H2SO4 + 2 Al Al2(SO4)3 + 3H2

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f. 2 C2H6 + 7 O2 4CO2 + 6H2O

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

h. SKIP P4 + KClO3 KCl + P2O5

ANSWERS:

1)1 + 3 22)2 2 + 33)2 + 1 2 + 14)2 + 1 25)1 + 2 2 + 16)2 + 3 6 + 17)1 + 2 1 + 28)1 + 5 3 + 49)2 + 25 16 + 1810) 1 + 3 1 + 311) 4 + 5 212) 2 + 2 2 + 113) 2 4 + 1

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14) 1 + 12 815) 6 + 6 1 + 616) 2 + 1 2 + 117) 2 + 1 1 + 1 + 118) 1 + 1 1 + 1 + 119) 2 + 1 220) 2 + 1 2 + 1

HOMEWORK: BALANCING CHEMICAL REACTIONS NAME:DATE:

1. ___P4 + _5__O2 _2__P2O5

2. _2__Al + _6__HCl _2__AlCl3 + _3__H2

3. ___Al2(SO4)3 + _3__Ca(OH)2 _2__Al(OH)3 + _3__CaSO4

4. _8__H2S + _8__Cl2 ___S8 + _16__HCl

5. _3___Mg + ____N2 ____Mg3N2

6. _3___Fe + _4___H2O ____Fe3O4 + _4___H2

7. _2___NaOH + ____Cl2 ____NaCl + ____NaClO + ____H2O

8. _2___C4H10 + _13___O2 _8___CO2 + _10___H2O

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9. __2___CH3OH + __3___O2 _2___CO2 + __4___ H2O

SYNTHESIS, DECOMPOSITION AND COMBUSTION REACTIONS

Types of Reactions: Synthesis, Decomposition and Combustion

Synthesis – A + B AB (1 product only)

Decomposition – AB A + B (1 reactant only)

Combustion of a hydrocarbon – CxHy + O2 CO2 + H2O

Practice:

Balance each reaction below. Then identify the reaction type.

a. H2 + Br2 2 HBr __synthesis______________

b. C4H8 + 6 O2 4 CO2 + 4 H2O __combustion____________

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c. 2 NaOH Na2O + H2O __decomposition__________

d. Ba(ClO3)2 BaCl2 + 3 O2 __decomposition__________

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

e. phosphorus + oxygen tetraphosphorus decoxide __ synthesis _____________

4 P + 5 O2 P4O10

f. pentane (C5H12) + oxygen carbon dioxide + water __ combustion ____________

C5H12 + 8 O2 5 CO2 + 6 H2O

g. magnesium chlorate magnesium chloride + oxygen ___ decomposition _________

Mg(ClO3)2 MgCl2 + 3 O2

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

___ decomposition _________CaCO3 CaO + CO2

i. the formation of calcium nitride from calcium and nitrogen ___ synthesis _____________

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3 Ca + N2 Ca3N2

j. sulfur trioxide mixes with water in the atmosphere to form sulfuric acid ___ synthesis ________

SO3 + H2O H2SO4

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HOMEWORK: SYNTHESIS, DECOMPOSITION AND COMBUSTION REACTIONS1. Classify each equation below as synthesis, decomposition or combustion. Then balance each equation.

__decomposition_________________ 1. 2 NaClO3 2 NaCl + 3 O2

__synthesis______________________ 2. 2 Cu + S Cu2S

__synthesis______________________ 3. 2 S + 3 O2 2 SO3

__combustion___________________ 4. 2 C3H6 + 9 O2 6 CO2 + 6 H2O

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

water_decomposition_______________________ 1. potassium hydroxide potassium oxide + hydrogen

2 KOH K2O + H2O

__combustion______________________ 2. dicarbon tetrahydride + oxygen carbon dioxide + water

C2H4 + 3 O2 2 CO2 + 2 H2O

__decomposition_____________________ 3. lithium chlorate lithium chloride + oxygen

2 LiClO3 2 LiCl + 3 O2

__synthesis______________________ 4. magnesium + nitrogen magnesium nitride

3 Mg + N2 Mg3N2

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

4 Al + 3 O2 2 Al2O3

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

Na2CO3 Na2O + CO2

__synthesis_____________________ 7. water and dinitrogen pentoxide combine to form nitric acidH2O + N2O5 2 HNO3

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NOTES: SINGLE DISPLACEMENT REACTIONS & DOUBLE DISPLACEMENT REACTIONS

1. Single Displacement Reactions (aqueous ONLY)metals:

standard: A(s) + BX (aq) AX (aq) + B(s)

example: Cu + 2 AgNO3 Cu(NO3)2 + 2 Ag

metal + acid:standard: A(s) + HX (aq) AX (aq) + H2(g)

example: Mg + 2 HCl MgCl2 + H2

metal + water:standard: A(s) + H2O(l) AOH(aq) + H2(g)

example: 2 K + 2 H2O 2 KOH + H2

halogens:standard: X2 + AY AX + Y2

example: F2 + 2 KI 2 KF + I2

2. Double Displacement (aqueous only)standard : AX (aq) + BY (aq) AY(aq) + BX(s)

example : Ba(NO3)2 + NaI BaI2 + NaNO3

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

_single displacement_ a. Ba + 2 AgNO3 Ba(NO3)2 + 2Ag

__single displacement________b. F2 + 2KI 2 KF + I2

__double displacement c. NaOH + CaCl2 _2 NaCl + Ca(OH)2

___single displacement d. Zn + H2SO4 ZnSO4 + H2

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CLASSIFICATION OF CHEMICAL REACTIONS

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

1. 2H2 + O2 2H2O_____synthesis_____________________

2. 2H2O 2H2 + O2______decomposition_______________

3. Zn + H2SO4 ZnSO4 + H2 ______single____________________

4. 2CO + O2 2CO2______synthesis____________________

5. 2HgO 2Hg + O2 _____decomposition__________

6. 2 KBr + Cl2 2 KCl + Br2 _____single_____________________

7. CaO + H2O Ca(OH)2____synthesis______________________

8. AgNO3 + NaCl AgCl + NaNO3 ____double______________________

9. 2 H2O2 2H2O + O2 ____decomposition_______________

10. Ca(OH)2 + H2SO4 CaSO4 + 2H2O___double_______________________

11. Copper metal is put into a solution of silver nitrate. Solid silver precipitates, and copper (II) nitrate solution is formed.Cu + 2 AgNO3 2 Ag + Cu(NO3)2 single displacement

12. Methane gas burns in pure oxygen to give carbon dioxide and waterCH4 + 2 O2 CO2 + 2 H2O combustion

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13. When sodium carbonate is heated, it breaks down to form sodium oxide and carbon dioxide.Na2CO3 Na2O + CO2 decomposition

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HOMEWORK – PRACTICE REACTION WRITING

Identify the reaction type for each reaction written below. Then write the balanced equation for each reaction.

____single displacement___ 1. Magnesium is placed in a solution of aluminum nitrate

3 Mg + 2 Al(NO3)3 3 Mg(NO3)2 + 2 Al

_______synthesis________________ 2. Calcium burns in pure oxygen.

2 Ca + O2 2CaO

____combustion hydrocarbon_____ 3. The combustion of propane (C3H8)

__________C3H8 + 5 O2 3 CO2 + 4 H2O_________________

____single displacement_____ 4. Fluorine is bubble through a solution of sodium bromide

__________F2 + 2 NaBr 2 NaF + Br2 _______________________________________

___double displacement______ 5. Solutions of potassium chloride and barium hydroxide are mixed.

_____2 KCl + Ba(OH)2 2 KOH + BaCl2 ______________________________

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WRITING WORD EQUATIONS

__decomposition_______________1. aluminum chlorate aluminum chloride + oxygen2 Al(ClO3)3 9 O2 + 2 AlCl3

__SR_______________ 2. lithium + iron (III) nitrate lithium nitrate + iron3 Li + Fe(NO3)3 3 LiNO3 + Fe

__decomposition_______________ 3. magnesium carbonate magnesium oxide + carbon dioxideMgCO3 MgO + CO2

__synthesis____________ 4. tin + nitrogen tin (IV) nitride3 Sn + 2 N2 Sn3N4

__SR____________ 5. Zinc reacts with nitric acid to form zinc nitrate and hydrogenZn + 2 HNO3 Zn(NO3)2 + H2

__decomposition__________6. calcium hydroxide breaks down to form calcium oxide and waterCa(OH)2 CaO + H2O

WRITING WORD EQUATIONS WITH PREDICTING PRODUCTS

__synthesis_______________ 1. aluminum + oxygen 4 Al + 3 O2 2 Al2O3

__SR____________ 2. sodium + silver nitrate Na + AgNO3 NaNO3 + Ag

__SR_______________ 3. magnesium + hydrochloric acid 2 Mg + 2 HCl 2 MgCl + H2

___DR______________ 4. solutions of iron (III) nitrate + potassium sulfate are mixed 2 Fe(NO3)3 + 3 K2(SO4)3 Fe2(SO4)3 + 6 KNO3

____SR_____________ 5. Chlorine gas is bubbled through a solution of lithium iodide Cl2 + 2 LiI 2 LiCl + I2

WRITING WORD EQUATIONS

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a. lithium + nitrogen lithium nitride

6 Li + N2 2 Li3N

b. aluminum + oxygen aluminum oxide

4 Al + 3 O2 2 Al2O3

c. sodium carbonate sodium oxide + carbon dioxide

Na2CO3 Na2O + CO2

d. zinc + phosphoric acid zinc phosphate + hydrogen gas

3 Zn + 2 H3PO4 Zn3(PO4)2 + 3 H2

e. chlorine gas + lithium iodide lithium chloride + iodine

Cl2 + 2 LiI 2 LiCl + I2

f. sodium hydroxide sodium oxide + water

2 NaOH Na2O + H2O

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

Mg + 2 HCl MgCl2 + H2

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

FeCl3 + 3 NaOH Fe(OH)3 + 3 NaCl

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

2 Na + 2 H2O 2NaOH + H2

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

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Zn + Pb(NO3)2 Zn(NO3)2 + Pb

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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 + __2__ NaNO3 2 AgNO3 + Na2SO4

2) __2__ NaI + ____ CaSO4 CaI2 + Na2SO4

3) __2__ HNO3 + ____ Ca(OH)2 2 H2O + Ca(NO3)2

4) ____ Zn + ___2__ HNO3 Zn(NO3)2 + H2

5) ____ AlCl3 + ____ (NH4)3PO4 AlPO4 + 3 NH4Cl

6) ___3_ Pb + ___2_ Fe(NO3)3 3 Pb(NO3)2 + 2 Fe

7) ___2_ C3H6 + __9__ O2 6 CO2 + 6 H2O

8) __2__ Na + ____ CaSO4 Na2SO4 + Ca

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