Unit 8 Review
1.
The balanced equation P4(s) + 6H2(g)
us that 4.0 mol H2
A) reacts with 2.0 mol P4
B) produces 8.0 mol PH3
C) cannot react with phosphorus
D) produces 2.7 mol PH3
E) reacts with 4.0 mol P4
 4PH3(g) tells
3.
A 1.3-mol sample of KClO3 was decomposed according
to the equation
2KClO3 (s)  2KCl(s)  3O2 (g)
How many moles of O2 are formed assuming 100% yield?
A) 0.9 mol
B) 1.1 mol
C) 1.3 mol
D) 0.7 mol
E) 2.0 mol
5.
The rusting of iron is represented by the equation 4Fe +
3O2  2Fe2O3. If you have a 1.58-mol sample of iron, how
many moles of Fe2O3 will there be after the iron has rusted
completely?
A) 0.527 mol
B) 0.790 mol
C) 1.05 mol
D) 1.58 mol
E) 2.37 mol
7.
Consider the following reaction, where X represents an
unknown element:
6X(s) + 2B2O3(s)  B4X3(s) + 3XO2(g)
11.
In the reaction N2(g) + 3H2(g)  2NH3(g), how many moles
of ammonia would be produced from 1.09 mol of hydrogen and excess
nitrogen?
A) 1.42 mol
B) 3.27 mol
C) 0.727 mol
D) 2.18 mol
E) 0.363 mol
13.
Refer to the following unbalanced equation:
C6H14 +
O2  CO2 + H2O
What mass of oxygen (O2) is required to react completely with 13.1 g of
C6H14?
A) 3.98  103 g
B) 23.1 g
C) 4.86 g
D) 46.2 g
E) 0.152 g
15.
How many molecules of carbon dioxide will be formed if 7.57 g
of propane is burned in the following reaction?
C3H8 (g)  5O2 (g)  3CO2 (g)  4H 2O(g)
A)
B)
C)
D)
E)
1.37  1025 molecules
1.03  1023 molecules
4.14  1023 molecules
3.10  1023 molecules
5.17  1023 molecules
18.
Calculate the mass of carbon dioxide produced from 25.7 g of
octane, C8H18, in the following reaction.
2C8 H18 (g)  25O2 (g)  16CO2 (g)  18H2O(g)
If 175 g of X reacts completely with diboron trioxide to produce
2.43 mol of B4X3, what is the identity of X?
A) Ge
B) Mg
C) Si
D) N
E) C
A)
B)
C)
D)
E)
79.2 g CO2
158 g CO2
89.1 g CO2
1.238 g CO2
1.800 g CO2
19.
Calculate the molecules of oxygen required to react with 18.2 g
of sulfur in the following reaction.
2S(s)  3O2 (g)  2SO3 (g)
9.
Refer to the following equation:
4NH3(g) +
7O2(g)  4NO2(g) + 6H2O(g)
How many molecules of NO2 are produced when 3.02 mol of
ammonia is completely reacted?
A) 12.08
B) 3.64  1024
C) 1.82  1024
D) 139
E) none of these
A)
B)
C)
D)
E)
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1.03  1024 molecules O2
2.28  1023 molecules O2
1.71  1023 molecules O2
3.42  1023 molecules O2
5.13  1023 molecules O2
20.
Consider the reaction
35.
2Fe(s)  3O2 (g)  Fe2O3 (s)
If 10.1 g of iron(III) oxide (rust) is produced from a certain
amount of iron, how many grams of oxygen are needed for this
reaction?
A) 3.04 g
B) 6.07 g
C) 1.35 g
D) 2.02 g
E) none of these
2S(s)  3O2 (g)  2SO3 (g)
how many moles of SO3 can be produced from 8.7 g O2 and excess S?
A) 0.36 mol SO3
B) 5.8 mol SO3
C) 0.18 mol SO3
D) 0.41 mol SO3
E) none of these
36.
24.
How many atoms of aluminum can be produced by the
decomposition of 97.6 g of Al 2O3?
(Hint: Write and balance the equation first.)
A) 2.31  1024 Al atoms
B) 1.15  1024 Al atoms
C) 5.76  1023 Al atoms
D) 2.88  1023 Al atoms
E) none of these
25.
Nitrogen and hydrogen gases are combined at high
temperatures and pressures to produce ammonia, NH3. If 103.1 g
of N2 are reacted with excess H2, how many moles of NH3 will be
formed?
A) 3.680 mol
B) 2.453 mol
C) 7.359 mol
D) 5.519 mol
E) none of these
27.
How many moles of O2 are required for the complete
reaction of 35.9 g of C2H4 to form CO2 and H2O?
A) 0.640 mol
B) 2.56 mol
C) 5.12 mol
D) 3.84 mol
E) none of these
29.
What number of moles of ammonia can be produced
from 9.93 g of hydrogen gas and excess nitrogen gas?
A) 1.642 mol NH3
B) 9.85 mol NH3
C) 6.57 mol NH3
D) 7.39 mol NH3
E) 3.28 mol NH3
34.
For the reaction
2S(s)  3O2 (g)  2SO3 (g)
how many moles of SO3 will be produced from 9.8 mol O2 and
excess S?
A) 14.7 mol SO3
B) 6.5 mol SO3
C) 9.8 mol SO3
D) 3.3 mol SO3
E) none of these
For the reaction
For the reaction
CaCO3 (s)  2HCl(aq)  CaCl2 (aq)  CO2 (g)  H 2O(l)
how many grams of CaCl2 can be obtained if 37.2 g HCl is allowed to
react with excess CaCO3?
A) 113 g CaCl2
B) 226 g CaCl2
C) 0.510 g CaCl2
D) 56.6 g CaCl2
E) none of these
39.
For the reaction
2Cl2(g) + 4NaOH(aq)  3NaCl(aq) + NaClO3(aq) + 2H2O(l)
how many molecules of H2O can be produced from 30.2 g of NaOH and
excess Cl2?
A) 9.09  1023 molecules H2O
B) 2.27  1023 molecules H2O
C) 1.14  1023 molecules H2O
D) 4.55  1023 molecules H2O
E) 6.06  1023 molecules H2O
42.
Fe3O4 reacts with CO according to the equation
Fe3O4 (s)  4CO(g)  4CO2 (g)  3Fe(s)
If 361.5 g CO is reacted with excess Fe3O4, what mass of CO2 will be
produced?
A) 1136.0 g CO2
B) 284.0 g CO2
C) 757.3 g CO2
D) 426.0 g CO2
E) 568.0 g CO2
43.
Consider the reaction
2CH4 (g)  3O2 (g)  2NH3 (g)  2HCN(g)  6H2O(g)
If 326.6 g NH3 is reacted with excess CH4 and O2, what mass of HCN
can be produced?
A) 518.2 g HCN
B) 1036.4 g HCN
C) 259.1 g HCN
D) 345.5 g HCN
E) none of these
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44.
Fe2O3 (molar mass = 159.7 g/mol) reacts with CO (molar
mass = 28.0 g/mol) according to the equation
54.
How many moles of SbCl3 is formed when 4.00 mol Sb are
reacted with 5.37 mol Cl2 according to the unbalanced equation
Fe2O3 (s)  3CO(g)  3CO2 (g)  2Fe(s)
When 111.1 g Fe2O3 reacts with excess CO, what number of
moles of Fe (iron) is produced?
A) 2.087 mol Fe
B) 1.391 mol Fe
C) 0.348 mol Fe
D) 2.783 mol Fe
E) none of these
45.
Fe2O3 (molar mass = 159.7 g/mol) reacts with CO (molar
mass = 28.0 g/mol) according to the equation
Fe2O3 (s)  3CO(g)  3CO2 (g)  2Fe(s)
When 280.4 g of CO reacts with excess Fe2O3, how many moles
of Fe (iron) will be produced?
A) 20.02 mol Fe
B) 3.337 mol Fe
C) 6.674 mol Fe
D) 15.02 mol Fe
E) 5.005 mol Fe
47.
For the reaction
CaCO3 (s)  2HCl(aq)  CaCl2 (aq)  CO2 (g)  H 2O(l)
39.7 g solid CaCO3 is mixed with 51.6 g HCl. What number of
grams of CO2 will be produced?
A) 14.1 g CO2
B) 34.9 g CO2
C) 8.7 g CO2
D) 31.1 g CO2
E) 17.5 g CO2
50.
Sodium and water react according to the equation
2Na(s)  2H2O(l)  2NaOH(aq)  H 2 (g)
What number of moles of H2 will be produced when 4.0 mol Na is
added to 2.7 mol H2O?
A) 1.4 mol
B) 5.4 mol
C) 2.0 mol
D) 2.7 mol
E) 8.0 mol
53.
For the reaction of C2H4(g) with O2(g) to form CO2(g)
and H2O(g), what number of grams of CO2 could be produced
from 2.0 g of C2H4 and 2.9 g of O2?
A) 6.0 g
B) 2.7 g
C) 4.0 g
D) 6.3 g
E) none of these
Sb  Cl2  SbCl3
A)
B)
C)
D)
E)
8.06 mol SbCl3
5.37 mol SbCl3
3.58 mol SbCl3
4.00 mol SbCl3
Cannot be determined based on the information given.
56.
Consider the equation: A + 3B  4C. If 3.0 moles of A is
reacted with 6.0 moles of B, which of the following is true after the
reaction is complete?
A) A is the leftover reactant because you need only 2 moles
of A and have 3.
B) A is the leftover reactant because for every 1 mole of A, 4
moles of C are produced.
C) B is the leftover reactant because you have more moles of
B than A.
D) B is the leftover reactant because 3 moles of B react with
every 1 mole of A.
E) Neither reactant is leftover.
58.
Consider the equation: A + 3B  2C. The molar mass of B
is 50.0 g/mol. Which of the following statements is true when equal
masses of A and B are reacted?
A) If the molar mass of A is greater than the molar mass of
B, then A must determine how much C is produced.
B) If the molar mass of A is less than the molar mass of B,
then A must determine how much C is produced.
C) If the molar mass of A is the same as the molar mass of B,
then A and B react in a perfect stoichiometric ratio and both
determine how much C is produced.
D) If the molar mass of A is greater than the molar mass of
B, then B must determine how much C is produced.
E) If the molar mass of A is less than the molar mass of B,
then B must determine how much C is produced.
59.
Consider that calcium metal reacts with oxygen gas in the air to
form calcium oxide. Suppose we react 6.00 mol calcium with 4.00 mol
oxygen gas. Determine the number of moles of calcium oxide produced
after the reaction is complete.
A) 6.00 mol CaO
B) 3.00 mol CaO
C) 4.00 mol CaO
D) 8.00 mol CaO
E) none of these
62.
You react 25.0 g hydrogen gas with 62.1 g oxygen gas.
Determine the mass of water that can be produced from these reactants.
A) 35.0 g H2O
B) 17.5 g H2O
C) 7.8 g H2O
D) 69.9 g H2O
E) 223 g H2O
Page 3
63.
Which of the following statements is always true
concerning a reaction represented by the following balanced
chemical equation?
2C2H6(g) + 7O2(g)  4CO2(g) + 6H2O(g)
A) If we have equal masses of C2H6 and O2, there is no
limiting reactant.
B) If we have an equal number of moles of C2H6 and
O2, there is no limiting reactant.
C) If we have more mass of C2H6, then O2 must be the
limiting reactant.
D) If we have more mass of O2, then C2H6 must be the
limiting reactant.
E) None of these statements (a-d) are true.
64.
Reacting 3.00 mol nitrogen gas with 6.20 mol hydrogen
gas will produce how many moles of ammonia according to the
following balanced chemical equation?
N2 (g)  3H2 (g)  2NH3 (g)
A)
B)
C)
D)
E)
6.20 mol NH3
9.30 mol NH3
4.13 mol NH3
12.40 mol NH3
6.00 mol NH3
65.
Consider a reaction in which two reactants make one
product (for example, consider the unbalanced reaction A + B 
C). You know the following:
2.0 mol A (with an excess of B) can produce a maximum of 2.0
mol C
3.0 mol B (with an excess of A) can produce a maximum of 4.0
mol C
If you react 2.0 mol A with 3.0 mol B, what is the maximum
amount of C that can be produced?
A) 2.0 mol
B) 4.0 mol
C) 5.0 mol
D) 6.0 mol
E) More information is needed to answer this question.
68.
Ammonia reacts with oxygen to form nitrogen dioxide
and water according to the following equation:
4NH3 (g)  7O2 (g)  4NO2 (g)  6H 2O(g)
You react ammonia and oxygen, and at the end of the experiment
you find that you produced 33.3 g of water and have 8.52 g of
ammonia left over. Determine the mass of oxygen reacted.
A) 50.7 g O2
B) 17.7 g O2
C) 59.1 g O2
D) 103.5 g O2
E) 69.0 g O2
69.
Consider the following reaction:
2A  B  3C  D
3.36 mol A and 2.00 mol B react to form 4.00 mol C. What is the
percent yield of this reaction?
A) 20.6%
B) 52.9%
C) 39.7%
D) 79.4%
E) 100.%
71.
When NH3 is prepared from 28 g N2 and excess H2, the
theoretical yield of NH3 is 34 g. When this reaction is carried out in a
given experiment, only 29 g is produced. What is the percentage yield?
(Ignore significant figures for this problem.)
A) 15%
B) 57%
C) 28%
D) 43%
E) 85%
72.
Tin(II) fluoride is added to some dental products to help prevent
cavities. Manufacturers have to make the tin(II) fluoride first, though,
before they can add it to their products.
Sn(s) + 2HF(aq)
 SnF2(aq) + H2(g)
How many grams of tin(II) fluoride can be made from 50.3 g of
hydrogen fluoride if there is plenty of tin available to react?
A) 197. g
B) 394. g
C) 788. g
D) 1.26 g
E) 101. g
73.
Consider the following unbalanced equation:
 Al(OH)3 + CH4
Al4C3 + H2O
How many moles of water are needed to react with 194. g of Al4C3?
A) 1.35 mol
B) 0.112 mol
C) 0.742 mol
D) 291. mol
E) 16.2 mol
80.
Na(s)
Consider the following unbalanced equation: Na2SiF6(s) +
 Si(s) + NaF(s)
How many grams of sodium are required to completely react with 0.335
mol Na2SiF6?
A) 0.335 g
B) 1.34 g
C) 1.93 g
D) 7.70 g
E) 30.8 g
Page 4
83.
Consider the following unbalanced equation:
C2H5OH(g) + O2(g)  CO2(g) + H2O(l)
If 1.87 g of ethanol reacts with 10.7 g of oxygen, how many moles
of water are produced?
A) 0.0406 mol
B) 0.122 mol
C) 0.0135 mol
D) 0.334 mol
E) 0.669 mol
85.
Consider the reaction of magnesium metal with
hydrochloric acid to produce magnesium chloride and hydrogen
gas. If 4.70 mol of magnesium and 4.70 mol of hydrochloric acid
are reacted, how many moles of hydrogen gas are produced?
A) 9.40 mol
B) 2.35 mol
C) 4.70 mol
D) 6.70 mol
E) none of these
87.
Consider the reaction of magnesium metal with hydrochloric
acid to produce magnesium chloride and hydrogen gas. If 3.32 mol of
magnesium and 3.32 mol of hydrochloric acid are reacted, how many
grams of magnesium chloride are produced?
A) 316. g
B) 632. g
C) 158. g
D) 198. g
E) 1.66 g
89.
Consider the reaction of magnesium metal with hydrochloric
acid to produce magnesium chloride and hydrogen gas. If 3.70 mol of
magnesium and 3.70 mol of hydrochloric acid are reacted, how many
grams of excess reactant are left over?
A) 1.85 g
B) 89.9 g
C) 67.4 g
D) 135. g
E) 45.0 g
Page 5
Answer Key
1.
D
3.
E
5.
B
7.
E
9.
C
11.
C
13.
D
15.
D
18.
A
19.
E
20.
B
24.
B
25.
C
27.
D
29.
E
34.
B
35.
C
36.
D
39.
B
42.
E
43.
A
44.
B
45.
C
47.
E
50.
A
53.
B
54.
C
56.
A
58.
E
59.
A
62.
D
63.
C
64.
C
65.
A
68.
E
69.
D
71.
E
72.
A
73.
E
80.
E
83.
B
85.
B
87.
C
89.
E
Page 2