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Chapter 9 exam

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 
Which branch of chemistry deals with the mass relationships of elements in compounds and the mass relationships among reactants and products in chemical reactions?
a.
qualitative analysis
c.
chemical kinetics
b.
entropy
d.
stoichiometry
 

 2. 
Which of the following would not be studied in the branch of chemistry called stoichiometry?
a.
the mole ratio of aluminum and chlorine in aluminum chloride
b.
the amount of energy required to break the ionic bonds in calcium fluoride
c.
the mass of carbon produced when a known mass of sucrose decomposes
d.
the number of moles of hydrogen that reacts completely with a known quantity of oxygen
 

 3. 
A balanced chemical equation allows one to determine the
a.
mole ratio of any two substances in the reaction.
b.
energy released in the reaction.
c.
electron configuration of all elements in the reaction.
d.
mechanism involved in the reaction.
 

 4. 
To balance a chemical equation, it may be necessary to adjust the
a.
coefficients.
c.
formulas of the products.
b.
subscripts.
d.
number of products.
 

 5. 
A chemical equation is balanced when the
a.
coefficients of the reactants equal the coefficients of the products.
b.
same number of each kind of atom appears in the reactants and in the products.
c.
products and reactants are the same chemicals.
d.
subscripts of the reactants equal the subscripts of the products.
 

 6. 
If one knows the mole ratio of a reactant and product in a chemical reaction, one can
a.
estimate the energy released in the reaction.
b.
calculate the speed of the reaction.
c.
calculate the mass of the product produced from a known mass of reactant.
d.
decide whether the reaction is reversible.
 

 7. 
In the chemical equation wA + xB ® yC + zD, if one knows the mass of A and the molar masses of A, B, C, and D, one can determine
a.
the mass of any of the reactants or products.
b.
the mass of B only.
c.
the total mass of C and D only.
d.
the total mass of A and B only.
 

 8. 
The units of molar mass are
a.
g/mol.
c.
amu/mol.
b.
mol/g.
d.
amu/g.
 

 9. 
For the reaction represented by the equation C + 2H2 ® CH4, how many moles of hydrogen are required to produce 10 mol of methane, CH4?
a.
2 mol
c.
10 mol
b.
4 mol
d.
20 mol
 

 10. 
For the reaction represented by the equation N2 + 3H2 ® 2NH3, how many moles of nitrogen are required to produce 18 mol of ammonia?
a.
9.0 mol
c.
27 mol
b.
18 mol
d.
36 mol
 
 
Use the table below to answer the following questions.

ElementSymbolAtomic Mass
BromineBr79.90
CalciumCa40.08
CarbonC12.01
ChlorineCl35.45
CobaltCo58.93
CopperCu63.55
FluorineF19.00
HydrogenH1.01
IodineI126.90
IronFe55.85
LeadPb207.2
MagnesiumMg24.30
MercuryHg200.59
NitrogenN14.01
OxygenO15.00
PotassiumK39.10
SodiumNa22.99
SulfurS32.01
 

 11. 
For the reaction represented by the equation 2Na + Cl2 ® 2NaCl, how many grams of chlorine gas are required to react completely with 2.00 mol of sodium?
a.
35.5 g
c.
141.8 g
b.
70.9 g
d.
212.7 g
 

 12. 
For the reaction represented by the equation 2HNO3 + Mg(OH)2 ® Mg(NO3)2 + 2H2O, how many grams of magnesium nitrate are produced from 8.00 mol of nitric acid, HNO3, and an excess of Mg(OH)2?
a.
148 g
c.
593 g
b.
445 g
d.
818 g
 

 13. 
For the reaction represented by the equation Cl2 + 2KBr ® 2KCl + Br2, how many moles of potassium chloride are produced from 119 g of potassium bromide?
a.
0.119 mol
c.
0.581 mol
b.
0.236 mol
d.
1.00 mol
 

 14. 
For the reaction represented by the equation 3Fe + 4H2O ® Fe3O4 + 4H2, how many moles of iron(III) oxide are produced from 500. g of iron in an excess of H2O?
a.
1.04 mol
c.
8.95 mol
b.
2.98 mol
d.
12.98 mol
 

 15. 
For the reaction represented by the equation 2KlO3 ® 2KCl + 3O2, how many moles of potassium chlorate are required to produce 250. g of oxygen?
a.
2.00 mol
c.
4.97 mol
b.
4.32 mol
d.
5.21 mol
 

 16. 
For the reaction represented by the equation 2Na + 2H2O ® 2NaOH + H2, how many grams of hydrogen are produced if 120. g of sodium and 80. g of water are available?
a.
4.5 g
c.
80. g
b.
45 g
d.
200 g
 

 17. 
For the reaction represented by the equation 2Na + Cl2 ® 2NaCl, how many grams of sodium chloride can be produced from 500. g each of sodium and chlorine?
a.
112 g
c.
409 g
b.
319 g
d.
824 g
 

 18. 
For the reaction represented by the equation SO3 + H2O ® H2SO4, how many grams of sulfuric acid can be produced from 200. g of sulfur trioxide and 100. g of water?
a.
100. g
c.
245 g
b.
200. g
d.
285 g
 

 19. 
Which reactant controls the amount of product formed in a chemical reaction?
a.
excess reactant
c.
composition reactant
b.
mole ratio
d.
limiting reactant
 

 20. 
A chemical reaction involving substances A and B stops when B is completely used. B is the
a.
excess reactant.
c.
primary reactant.
b.
limiting reactant.
d.
primary product.
 

 21. 
To determine the limiting reactant in a chemical reaction, one must know the
a.
available amount of one of the reactants.
c.
available amount of each reactant.
b.
amount of product formed.
d.
speed of the reaction.
 

 22. 
After calculating the amount of reactant B required to completely react with A, then comparing that amount with the amount of B available, one can determine the
a.
limiting reactant.
c.
energy released in the reaction.
b.
rate of the reaction.
d.
pathway of the reaction.
 

 23. 
What is the maximum possible amount of product obtained in a chemical reaction?
a.
theoretical yield
c.
mole ratio
b.
percentage yield
d.
actual yield
 

 24. 
If the percentage yield is equal to 100%, then
a.
the actual yield is greater than the theoretical yield.
b.
the actual yield is equal to the theoretical yield.
c.
the actual yield is less than the theoretical yield.
d.
there was no limiting reactant.
 

 25. 
For the reaction represented by the equation CH4 + 2O2 ® 2H2O + CO2, calculate the percentage yield of carbon dioxide if 1000. g of methane react with excess oxygen to produce 2300. g of carbon dioxide.
a.
83.88%
c.
92.76%
b.
89.14%
d.
96.78%
 



 
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