Coyle/Tang-Johnson
Chemistry Study Guide
Chapter 11 Study Guide- Chemical Reactions
TEST: Thursday 2/17/11
11.1 Describing Chemical Reactions
Define the following terms:
- chemical equation
- skeleton equation
- catalyst
- coefficients
- balanced equation
_____________
REACTANTS
(what you start with)

yields
______________
PRODUCTS
(what you end up with)
Commonly used symbols:
(g)= ________________
 = __________________
(s) = ________________
N.R = ________________
(1) = ________________
(aq)= _________________
Some things to remember about writing equations:
1. When diatomic elements stand alone, they are always written as H2, N2, O2, F2, Cl2, Br2, I2
2. The sign, → , means "yields" and shows the direction of the action.
3. A small delta, () or the word “heat”, above the arrow shows that heat has been added.
4. A double arrow, ↔ , shows that the reaction is reversible and can go in both directions.
5. Before beginning to balance an equation, check each formula to see that it is correct. Do so by
checking the charge on each ion and using the criss-cross method.
6. Balancing is done by placing coefficients in front of the formulas to insure the same number of
atoms of each element on both sides of the arrow. NEVER change a formula during the
balancing of an equation.
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Chemistry Study Guide
Rules for Balancing Equations:
1. Write the complete formula with the reactants on the left and products on the right.
2. Count the number of atoms of each element on each side of the equation.
3. Balance the number of atoms by adding coefficients (the number in front of the formula);
do NOT change subscripts to balance.
4. Make sure all coefficients are in the lowest possible ratio.
* Always leave the O2 or H2O for last
* When balancing equations that have compounds with polyatomic ions, consider the polyatomic
ion as a unit.
* Always consult the Activity Series of metals and nonmetals before attempting to write
equations for replacement reactions.
* If a reactant or product is a solid, (s) is placed after the formula.
* If a reactant or product is a gas, (g) is placed after it.
* If a reactant or product is in water solution, (aq) is placed after it.
PRACTICE: Rewrite the following word equations and balance them.
1. zinc + lead (II) nitrate yields zinc nitrate + lead
2. sodium phosphate + calcium chloride yields calcium phosphate + sodium chloride
11.2 Types of Chemical Reactions
1. Synthesis (Combination or Composition)
A synthesis reaction is when there is a combination of two or more substances and a compound
results. An example of a synthesis reaction is as follows:
A + B  AB
2. Decomposition
Decomposition is the opposite of synthesis. It is when a compound is broken down into simpler
substances, usually through electrolysis. An example of decomposition is as follows:
AB  A + B
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Chemistry Study Guide
3. Single Replacement
In a single replacement reaction, there is a rule that is always followed. A metal replaces a metal,
or a nonmetal replaces a nonmetal. An example of a single replacement reaction is as follows:
A + BC  AC + B
*** For an element to replace another lone element, it must be more active than the element it is
replacing.
4. Double Replacement Reactions
In a double replacement reaction, this rule is always followed. A metal replaces a metal, and a
nonmetal replaces a nonmetal. An example of a double replacement reaction is as follows:
AB + XY  AY + XB
*** For a double replacement reaction to occur, at least ONE of the following must happen:
1. One precipitate is formed (an insoluble or slightly insoluble solid)
 Check the solubility chart on the back of the periodic table
2. A molecular compound is formed (usually H2O)
3. A gas is formed
5. Combustion
A combustion reaction is when all substances in a compound are combined with oxygen, which
then produces carbon dioxide and water. Combustion is commonly called burning. It is an
exothermic reaction, which means heat is produced and is easily distinguished. Combustion
occurs predominantly in automobiles, homes, and in factories. An example of a combustion
reaction is as follows:
CxHy + O2  CO2 + H2O
11.3 Reactions in Aqueous Solutions
Define the following terms:
- complete ionic equation
- spectator ion
- net ionic equation
*** See p. 342 for an example of complete and net ionic equations ***
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Chemistry Study Guide
MIXED PRACTICE: Identify the type and balance the following equations and determine
whether the reaction will occur (Label precipitates and aqueous solutions for double replacement
reactions)
Cl2 
1.
AlBr3
+
2.
NaOH
+
HCl 
3.
NaCl
+
AgNO3
4.
C2H5OH
5.
Zn
+ HCl
6.
Ca
+ H2O →
7.
ZnO + HCl →
8.
CuSO4
9.
Cu2S
Br2
NaCl
+ H2O
 NaNO3
O2 
+
+
AlCl3 +

ZnCl2
+
H2O
+ H2
Ca(OH) 2 + H2
ZnCl2 +
Fe →
+ O2
CO2
+ AgCl
H2O
Fe2(SO4)3
→
Cu2O
+ Cu
+ SO2
10.
C2H4
+ O2
→
CO2 +
H2O
11.
C2H4
+
O2
→
CO
H2O
12.
Zn
+
O2
→
ZnO
13.
Na2CO3
14.
C4H8 (g)
15.
BaCl2 (aq)
16.
F2 (g)
+
→
Na2O
+
+
CO2
+ O2 (g) 
+
H2SO4 (aq) 
KCl (aq) 
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Chemistry Study Guide
Single Replacement Reactions
Balance and Predict the following products (**Remember to use your Activity
Series of Metals Chart**)
MgCl2 (aq) →
1.
Ni (s) +
2.
Fe (s) + CuSO4 (aq) →
3.
Br2 (aq) + KCl (aq) →
4.
Al (s) + Fe2O3(s) →
5.
Zn (s) + CuSO4(aq) →
Double Replacement Reactions
Balance and Predict the following products (**Remember to use your Solubility
Chart**)
1.
FeCl 2 (aq) + K 2S (aq) →
2. AlCl3 (aq) + Na 2CO3 (aq) →
3.
ZnSO4(aq) + SrCl2 (aq) →
4.
Pb(NO3) 2 (aq) + KI (aq) →
5.
KCl(aq) + AgNO3(aq) →
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Chemistry Study Guide
PRACTICE: a) Write the correct formula for each reaction, b) Balance the
equation, and c) Label the type of reaction
1. sulfur trioxide and water combine to make sulfuric acid.
2. lead II nitrate and sodium iodide react to make lead iodide and sodium nitrate.
3. calcium fluoride and sulfuric acid make calcium sulfate and hydrogen fluoride
4. calcium carbonate will come apart when heated to leave calcium oxide and carbon dioxide.
5. ammonia gas when it is pressed into water will make ammonium hydroxide.
6. sodium hydroxide neutralizes carbonic acid
7. zinc sulfide and oxygen become zinc oxide and sulfur.
8. lithium oxide and water make lithium hydroxide
9. aluminum hydroxide and sulfuric acid neutralize to make water and aluminum sulfate.
10. sulfur burns in oxygen to make sulfur dioxide.
11. barium hydroxide and sulfuric acid make water and barium sulfate.
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Chemistry Study Guide
12. aluminum sulfate and calcium hydroxide become aluminum hydroxide and calcium sulfate.
13. copper metal and silver nitrate react to form silver metal and copper II nitrate.
14. sodium metal and chlorine react to make sodium chloride.
15. calcium phosphate and sulfuric acid make calcium sulfate and phosphoric acid.
16. phosphoric acid plus sodium hydroxide.
17. propane burns (with oxygen)
18. zinc and copper II sulfate yield zinc sulfate and copper metal
19. sulfuric acid reacts with zinc
20. acetic acid ionizes.
21. steam methane to get hydrogen and carbon dioxide
22. calcium oxide and aluminum make aluminum oxide and calcium
23. chlorine gas and sodium bromide yield sodium chloride and bromine
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Chemistry Study Guide
ANSWERS TO EQUATIONS on p. 6 & 7
1. SO3 + H2O
SYNTHESIS
H2SO4
2. Pb(NO3)2 + 2NaI
PbI2 + 2NaNO3
DOUBLE REPLACEMENT (lead II iodide precipitates)
3. CaF2 + H2SO4
CaSO4 + 2 HF
DOUBLE REPLACEMENT (calcium sulfate precipitates)
4. CaCO3
CaO + CO2
DECOMPOSITION
5. NH3 + H2O
SYNTHESIS
NH4OH
6. 2 NaOH + H2CO3
Na2CO3 + 2 H2O
DOUBLE REPLACEMENT OR ACID-BASE NEUTRALIZATION
7. 2 ZnS + O2
2 ZnO + 2 S
SINGLE REPLACEMENT
8. Li2O + H2O
SYNTHESIS
2 LiOH
9. 2 Al(OH)3 + 3 H2SO4
6 H2O + Al2(SO4)3
DOUBLE REPLACEMENT OR ACID-BASE NEUTRALIZATION
10. S + O2
SO2
SYNTHESIS
11. Ba(OH)2 + H2SO4
2 H2O + BaSO4
DOUBLE REPLACEMENT OR ACID-BASE NEUTRALIZATION
12. Al2(SO4)3 + 3 Ca(OH)2
2 Al(OH)3 + 3 CaSO4
DOUBLE REPLACEMENT
(BOTH calcium sulfate and aluminum hydroxide are precipitate.)
13. Cu + 2AgNO3
2Ag + Cu(NO3)2
SINGLE REPLACEMENT
14. 2Na + Cl2
SYNTHESIS
2 NaCl
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Chemistry Study Guide
15. Ca3(PO4)2 + 3 H2SO4
3 CaSO4 + 2 H3PO4
DOUBLE REPLACEMENT
16. H3(PO4) + 3 NaOH
Na3PO4 + 3 H2O
DOUBLE REPLACEMENT (NEUTRALIZATION)
17. C3H8 + 5 O2
4 H2O + 3 CO2
BURNING OF A HYDROCARBON (COMBUSTION)
18. Zn + CuSO4
ZnSO4 + Cu
SINGLE REPLACEMENT
19. H2SO4 + Zn
ZnSO4 + H2
SINGLE REPLACEMENT
20. HC2H3O2
H+ + (C2H3O2)IONIZATION (NOTICE THAT IT IS REVERSIBLE)
21. 2 H2O + CH4
4 H2 + CO2
22. 3 CaO + 2 Al
Al2O3 + 3 Ca
SINGLE REPLACEMENT
23. Cl2 + 2 NaBr
2 NaCl + Br2
SINGLE REPLACEMENT
HELPFUL LINKS:
Types of Equations: Summarizes the different types of equations and give examples:
http://www.files.chem.vt.edu/RVGS/ACT/notes/Types_of_Equations.html
Review of process to balance equations & extra practice:
http://richardbowles.tripod.com/chemistry/balance.htm
Another review of balancing equations & extra practice:
http://misterguch.brinkster.net/eqnbalance.html
Practice identifying types of reactions:
http://www.sciencegeek.net/Chemistry/taters/EquationIdentification.htm
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