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CHAPTER 11 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

Δ heat

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ENERGY OF CHEMICAL REACTIONS:

Exothermic Reaction: ΔH is – Endothermic Reaction: ΔH = +

(heat is a “product”) (heat is a “reactant”)

Energy

Time

Energy

Time

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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 + O

H – 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

magnesium chloride and hydrogen.

Formula equation: ____ Mg + HCl MgCl2 + H2 __________________________________

diagram: Mg + H – Cl Cl-1

Mg+2

Cl-1

+ H – H

H – Cl

balanced reaction _______ Mg + 2 HCl MgCl2 + H2 ________________________________

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Try balancing these chemical reactions:

a. 2 Na + H2SO4 Na2SO4 + H2

b. 2 K + Cl2 2 KCl

c. S8 + 8 O2 8 SO2

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

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

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

g. C4H8 + 6 O2 4 CO2 + 4 H2O

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

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Balancing Chemical Equations Balance the equations below: 1) ____ N2 + ____ H2 ____ NH3 2) ____ KClO3 ____ KCl + ____ O2 3) ____ NaCl + ____ F2 ____ NaF + ____ Cl2 4) ____ H2 + ____ O2 ____ H2O 5) ____ Pb(OH)2 + ____ HCl ____ H2O + ____ PbCl2 6) ____ AlBr3 + ____ K2SO4 ____ KBr + ____ Al2(SO4)3

7) ____ CH4 + ____ O2 ____ CO2 + ____ H2O 8) ____ C3H8 + ____ O2 ____ CO2 + ____ H2O 9) ____ C8H18 + ____ O2 ____ CO2 + ____ H2O 10) ____ FeCl3 + ____ NaOH ____ Fe(OH)3 + ____NaCl 11) ____ P + ____O2 ____P2O5 12) ____ Na + ____ H2O ____ NaOH + ____H2 13) ____ Ag2O ____ Ag + ____O2 14) ____ S8 + ____O2 ____ SO3 15) ____ CO2 + ____ H2O ____ C6H12O6 + ____O2 16) ____ K + ____ MgBr ____ KBr + ____ Mg 17) ____ HCl + ____ CaCO3 ____ CaCl2 + ____H2O + ____ CO2 18) ____ HNO3 + ____ NaHCO3 ____ NaNO3 + ____ H2O + ____ CO2 19) ____ H2O + ____ O2 ____ H2O2 20) ____ NaBr + ____ CaF2 ____ NaF + ____ CaBr2

ANSWERS:

1) 1 + 3 2

2) 2 2 + 3

3) 2 + 1 2 + 1

4) 2 + 1 2

5) 1 + 2 2 + 1

6) 2 + 3 6 + 1

7) 1 + 2 1 + 2

8) 1 + 5 3 + 4

9) 2 + 25 16 + 18

10) 1 + 3 1 + 3

11) 4 + 5 2

12) 2 + 2 2 + 1

13) 2 4 + 1

14) 1 + 12 8

15) 6 + 6 1 + 6

16) 2 + 1 2 + 1

17) 2 + 1 1 + 1 + 1

18) 1 + 1 1 + 1 + 1

19) 2 + 1 2

20) 2 + 1 2 + 1

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SYNTHESIS, DECOMPOSITION AND COMBUSTION REACTIONS

Types of Reactions: Synthesis (Combination), Decomposition and Combustion

Synthesis (Combination) – 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____________

c. 2 NaOH Na2O + H2O __decomposition__________

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

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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 _____________

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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NOTES: SINGLE REPLACEMENT REACTIONS & DOUBLE REPLACEMENT 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 + 2 Ag

__single displacement________b. F2 + 2 KI 2 KF + I2

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

___single displacement d. Zn + H2SO4 ZnSO4 + H2

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WRITING WORD EQUATIONS

__decomposition_______________1. aluminum chlorate aluminum chloride + oxygen

2 Al(ClO3)3 9 O2 + 2 AlCl3

__SR_______________ 2. lithium + iron (III) nitrate lithium nitrate + iron

3 Li + Fe(NO3)3 3 LiNO3 + Fe

__decomposition_______________ 3. magnesium carbonate magnesium oxide + carbon dioxide

MgCO3 MgO + CO2

__synthesis____________ 4. tin + nitrogen tin (IV) nitride

3 Sn + 2 N2 Sn3N4

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

__decomposition__________6. calcium hydroxide breaks down to form calcium oxide and water Ca(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

Mg + 2 HCl MgCl2 + H2

___DR______________ 4. solutions of iron (III) nitrate + potassium sulfate are mixed

2 Fe(NO3)3 + 3 K2SO4 Fe2(SO4)3 + 6 KNO3

____SR_____________ 5. Chlorine gas is bubbled through a solution of lithium iodide

Cl2 + 2 LiI 2 LiCl + I2

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PREDICTING PRODUCTS

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) ____ Ca + ____ Na2SO4 CaSO4 + 2 Na

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PREDICTING PRODUCTS FOR THREE TYPES OF DECOMPOSITION

REACTIONS:

Try: a. strontium carbonate

______strontium oxide + carbon dioxide____________________

____SrCO3 SrO + CO2_____________________________________________________

b. aluminum carbonate

_____aluminum oxide + carbon dioxide____________________

____Al2(CO3)3 Al2O3 + 3 CO2_________________________________________________

Try: a. calcium hydroxide

_______calcium oxide + water_______________________________

________Ca(OH)2 CaO + H2O__________________________________________________________

b. Iron(III) hydroxide

______iron (III) oxide + water_______________________________

______2 Fe(OH)3 Fe2O3 + 3 H2O____________________________________________________

1. metal carbonate

metal oxide + carbon dioxide

example: sodium carbonate

sodium oxide + carbon dioxide

Na2CO3

Na2O + CO2

2. metal hydroxide

metal oxide + water

example: sodium hydroxide

sodium oxide + water

2 NaOH

Na2O + H2O

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Try: a. barium chlorate

_____barium chloride + oxygen____________________________

_______Ba(ClO3)2 BaCl2 + 3 O2_____________________________________________________

b. lithium chlorate

________lithium chloride + oxygen____________________________

_______2 LiClO3 2 LiCl + 3 O2___________________________________________________________

3. metal chlorate

metal chloride + oxygen

example: sodium chlorate

sodium chloride + oxygen

2 NaClO3

2 NaCl + 3 O2

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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

3. Concentration

Number of particles in a given volume affects rate of concentration – more particles, more collisions

4. Adding a Catalyst or Inhibitor

a catalyst speeds up a reaction by lowering the required activation energy

an inhibitor slows down a reaction by raising the activation energy

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WRITING WORD EQUATIONS

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

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

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SUMMARY - Predicting Products of Chemical Reactions

Class of reaction Reactants Probable products

Synthesis 2 or more substances 1 compound

Decomposition 1 compound 2 or more elements and/or compounds

Combustion Metal and oxygen

Nonmetal and oxygen

Compound and oxygen

Metal oxide

Nonmetal oxide

2 or more oxides

Single Replacement Metal and a compound

Nonmetal and a compound

New compound and the replaced metal

New compound and the replaced nonmetal

Double Replacement 2 compounds 2 different compounds, 1 or which is either a

precipitate, a gas, or water

Identifying Reaction Type Cheat Sheet Reaction Type Clue

Synthesis 1 product

Decomposition 1 reactant

Combustion CxHy + O2 CO2 + H2O

Single Replacement element + compound element + compound

Double Replacement compound + compound compound + compound