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A)
3 6 6 3 4
B)
8 6 5 10 5
C)
5 10 10 5 5
D)
1 2 2 1 1
E)
none of these
76. When the following equation is balanced, what is the sum of the coefficients?
Al2(SO4)3 + Ca(OH)2 → Al(OH)3 + CaSO4
A)
4
B)
9
C)
8
D)
7
E)
10
77. When balancing a chemical equation, it is generally best to start with the least complicated
molecules.
78. To balance a chemical equation, the coefficients must not be changed.
79. You heat 3.869 g of a mixture of Fe3O4 and FeO to form 4.141 g Fe2O3. The mass of oxygen
reacted is
A)
0.272 g
B)
0.476 g
C)
1.242 g
D)
1.000 g
E)
none of these
80. The Claus reactions, shown below, are used to generate elemental sulfur from hydrogen
sulfide.
2H2S + 3O2 → 2SO2 + 2H2O
SO2 + 2H2S → 3S + 2H2O
How much sulfur (in grams) is produced from 21.5 grams of O2?
A)
97.0 g
B)
14.4 g
C)
21.5 g
D)
43.1 g
E)
none of these
81. A chemical reaction has the equation: 2A + B → C. Which of the following figures best
illustrates a stoichiometric ratio of A and B?
I. II. III. IV.
A)
I only
B)
II only
C)
III only
D)
IV only
E)
both I and IV
82. When 233.1 g of ethylene (C2H4) burns in oxygen to give carbon dioxide and water, how
many grams of CO2 are formed?
A)
731.4 g
B)
365.7 g
C)
182.9 g
D)
8.31 g
E)
299.4 g
83. What would be the g Al / mole S ratio for the product of a reaction between aluminum and
sulfur?
A)
26.98 g Al / mol S
B)
53.96 g Al / mol S
C)
80.94 g Al / mol S
D)
17.99 g Al / mol S
E)
40.47 g Al / mol S
84. A 7.11-g sample of potassium chlorate was decomposed according to the following
equation:
2KClO3 → 2KCl + 3O2
How many moles of oxygen are formed?
A)
2.78 g
B)
0.0580 mol
C)
0.0387 mol
D)
0.0870 mol
E)
none of these
85. How many grams of Ca(NO3)2 can be produced by reacting excess HNO3 with 6.33 g of
Ca(OH)2?
A)
7.01 g
B)
14.0 g
C)
28.0 g
D)
12.7 g
E)
6.33 g
86. Sulfuric acid may be produced by the following process:
4FeS2 + 11O2 → 2Fe2O3 +8SO2
2SO2 +O2 → 2SO3
SO3 + H2O → H2SO4
How many moles of H2SO4 will be produced from 8.41 moles of FeS2?
A)
46.3
B)
8.41
C)
16.8
D)
4.21
E)
2.10
87. Reaction of methane with oxygen really proceeds in two steps:
A sample of CH4 is burned in an excess of O2 to give 3.0 moles of H2O. How many moles
of CH4 were in the original sample?
A)
1.5
B)
2.0
C)
6.0
D)
0.8
E)
3.0
88. Iron is produced from its ore by the reactions:
How many moles of O2(g) are needed to produce 4.6 moles of Fe(s)?
A)
2.3 mole O2
B)
3.5 mole O2
C)
4.6 mole O2
D)
6.9 mole O2
E)
13.8 mole O2
89. The refining of aluminum from bauxite ore (which contains 50.% Al2O3 by mass) proceeds
by the overall reaction 2Al2O3 + 3C → 4Al + 3CO2. How much bauxite ore is required to
give the 5.0 1013 g of aluminum produced each year in the United States? (Assume 100%
conversion.)
A)
1.3 1013 g
B)
5.3 1013 g
C)
1.9 1014 g
D)
7.6 1014 g
E)
none of these
90. Consider the following reaction:
What mass of CCl4 is formed by the reaction of 5.14 g of methane with an excess of
chlorine?
A)
12.3 g
B)
0.54 g
C)
791 g
D)
49.3 g
E)
none of these
91. One commercial system removes SO2 emissions from smoke at 95.0°C by the following set
of balanced reactions:
SO2 + Cl2 → SO2Cl2
SO2Cl2 + 2H2O → H2SO4 + 2HCl
H2SO4 + Ca(OH)2 → CaSO4 + 2H2O
Assuming the process is 95.0% efficient, how many grams of CaSO4 may be produced from
100. grams of SO2?
(molar masses: SO2, 64.1 g/mol; CaSO4, 136 g/mol)
A)
44.8 g
B)
47.1 g
C)
87.2 g
D)
202 g
E)
212 g
92. When rubidium metal is exposed to air, two atoms of rubidium, Rb, combine with one atom
of oxygen. If 1.98 grams of rubidium is exposed to air, what will be the mass of the product
in grams?
A)
17.98 g
B)
2.17 g
C)
9.98 g
D)
8.66 g
E)
4.33 g
93. The following two reactions are important in the blast furnace production of iron metal from
iron ore (Fe2O3):
Using these balanced reactions, how many moles of O2 are required for the production of
3.19 kg of Fe?
A)
42.8 moles
B)
19.0 moles
C)
171 moles
D)
57.1 moles
E)
2.39 moles
94. Nitric oxide, NO, is made from the oxidation of NH3, and the reaction is represented by the
equation:
4NH3 + 5O2 → 4NO + 6H2O
What mass of NO can be produced from 7.55 g of NH3?
A)
4.28 g NO
B)
13.3 g NO
C)
7.55 g NO
D)
20.0 g NO
E)
16.6 g NO
95. Nitric oxide, NO, is made from the oxidation of NH3, and the reaction is represented by the
equation:
4NH3 + 5O2 → 4NO + 6H2O
What mass of O2 would be required to react completely with 6.85 g of NH3?
A)
4.56 g O2
B)
10.3 g O2
C)
8.04 g O2
D)
16.1 g O2
E)
12.9 g O2
96. For the reaction P4O10(s) + 6H2O(l) → 4H3PO4(aq), what mass of P4O10 must be consumed
if 3.71 1023 molecules of H2O are also consumed?
A)
1.05 103 g P4O10
B)
29.1 g P4O10
C)
175 g P4O10
D)
1.85 g P4O10
E)
66.6 g P4O10
97. The limiting reactant in a reaction
A)
has the lowest coefficient in a balanced equation
B)
is the reactant for which you have the fewest number of moles
C)
has the lowest ratio of moles available/coefficient in the balanced equation
D)
has the lowest ratio of coefficient in the balanced equation/moles available
E)
none of these
98. Phosphoric acid can be prepared by reaction of sulfuric acid with “phosphate rock”
according to the equation:
Ca3(PO4)2 + 3H2SO4 → 3CaSO4 + 2H3PO4
Suppose the reaction is carried out starting with 129 g of Ca3(PO4)2 and 97.4 g of H2SO4.
Which substance is the limiting reactant?
A)
Ca3(PO4)2
B)
H2SO4
C)
CaSO4
D)
H3PO4
E)
none of these
99. Suppose the reaction Ca3(PO4)2 + 3H2SO4 → 3CaSO4 + 2H3PO4 is carried out starting with
153 g of Ca3(PO4)2
and 76.8 g of H2SO4. How much phosphoric acid will be produced?
A)
76.7 g
B)
51.1 g
C)
229.8 g
D)
115.1 g
E)
96.7 g
100. Phosphorus, P4, can be prepared from calcium phosphate by the reaction
3370 g
1795 g
650 g
2Ca3(PO4)2
+
6SiO2
+
10C
→ 6CaSiO3 + P4 + 10CO
310 g/mol
60.1 g/mol
12.0 g/mol
The molar mass for each reactant is shown below the reactant, and the mass of each reactant
for this problem is given above. Which reactant is the limiting reagent?
A)
C
B)
SiO2
C)
Ca3(PO4)2
D)
P4
E)
More information is needed.
101. SO2 reacts with H2S as follows:
2H2S + SO2 → 3S + 2H2O
When 7.50 g of H2S reacts with 12.75 g of SO2, which statement applies?
A)
6.38 g of sulfur are formed.
B)
10.6 g of sulfur are formed.
C)
0.0216 moles of H2S remain.
D)
1.13 g of H2S remain.
E)
SO2 is the limiting reagent.
102. How many grams of H2O will be formed when 32.0 g H2 is mixed with 12.0 g of O2 and
allowed to react to form water?
A)
13.5 g
B)
286 g
C)
6.8 g
D)
3.4 g
E)
144 g
103. A 15-g sample of lithium is reacted with 15 g of fluorine to form lithium fluoride:
2Li + F2 → 2LiF. After the reaction is complete, what will be present?
A)
2.16 moles lithium fluoride only
B)
0.789 moles lithium fluoride only
C)
2.16 moles lithium fluoride and 0.395 moles fluorine
D)
0.789 moles lithium fluoride and 1.37 moles lithium
E)
none of these
104. Consider the fermentation reaction of glucose:
A 1.00-mole sample of C6H12O6 was placed in a vat with 100 g of yeast. If 32.3 grams of
C2H5OH was obtained, what was the percent yield of C2H5OH?
A)
35.1%
B)
17.5%
C)
100%
D)
32.3%
E)
none of these
105. A 5.95-g sample of AgNO3 is reacted with BaCl2 according to the equation
to give 3.17 g of AgCl. What is the percent yield of AgCl?
A)
45.0%
B)
53.3%
C)
31.6%
D)
63.1%
E)
100%
106. The reaction of 11.9 g of CHCl3 with excess chlorine produced 10.2 g of CCl4, carbon
tetrachloride:
What is the percent yield?
A)
100%
B)
33.2%
C)
66.3%
D)
86%
E)
44.2%
107. When 20.0 g C2H6 and 60.0 g O2 react to form CO2 and H2O, how many grams of water are
formed?
A)
14.5 g
B)
18.0 g
C)
58.0 g
D)
20.0 g
E)
none of these
108. Given the equation 3A + B → C + D, you react 2 moles of A with 1 mole of B. Which of the
following is true?
A)
A is the limiting reactant because of its higher molar mass.
B)
A is the limiting reactant because you need 3 moles of A and have 2.
C)
B is the limiting reactant because you have fewer moles of B than A.
D)
B is the limiting reactant because 3 A molecules react with 1 B molecule.
E)
Neither reactant is limiting.
109. The following equation describes the oxidation of ethanol to acetic acid by potassium
permanganate:
5.00 g of ethanol and an excess of aqueous KMnO4 are reacted, and 4.24 g of HC2H3O2
result. What is the percent yield?
A)
100%
B)
65.1%
C)
21.7%
D)
34.9%
E)
4.24 g HC2H3O2 is impossible since it represents more than 100% yield.
110. Consider the following reaction:
What mass of CCl4 will be formed if 1.20 moles of methane react with 1.11 moles of
chlorine?
A)
185 g
B)
171 g
C)
683 g
D)
42.7 g
E)
19.7 g
111. The limiting reactant in a reaction
A)
is the reactant for which there is the least amount in grams
B)
is the reactant which has the lowest coefficient in a balanced equation
C)
is the reactant for which there is the most amount in grams
D)
is the reactant for which there is the fewest number of moles
E)
none of the above
112. The limiting reactant is the reactant
A)
for which you have the lowest mass in grams
B)
which has the lowest coefficient in the balanced equation
C)
which has the lowest molar mass
D)
which is left over after the reaction has gone to completion
E)
none of the above
113. Consider the following reaction:
2A + B → 3C + D
3.0 mol A and 2.0 mol B react to form 4.0 mol C. What is the percent yield of this reaction?
A)
50%
B)
67%
C)
75%
D)
89%
E)
100%
114. A chemical reaction has the equation: 2A + B → C. In which case is B the limiting reactant?
A)
I
B)
II
C)
III
D)
IV
E)
none of these
115. Which of the following statements is always true concerning a reaction represented by the
following balanced chemical equation?
2C2H6(g) + 7O2(g) → 6H2O(l) + 4CO2(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 limiting.
D)
If we have more mass of O2, then C2H6 must be limiting.
E)
None of these statements are true.
116. Equal masses (in grams) of hydrogen gas and oxygen gas are reacted to form water. Which
substance is limiting?
A)
Oxygen gas is limiting.
B)
Hydrogen gas is limiting.
C)
Water is limiting.
D)
Nothing is limiting.
E)
More information is needed to answer this question.
117. If 45.0 g of O2 are mixed with 45.0 g of H2 and the mixture is ignited, what mass of water is
produced?
A)
45.0 g
B)
50.7 g
C)
79.9 g
D)
25.3 g
E)
90.0 g
118. For the reaction N2(g) + 2H2(g) → N2H4(l), if the percent yield for this reaction is 82.0%,
what is the actual mass of hydrazine (N2H4) produced when 25.57 g of nitrogen reacts with
4.45 g of hydrogen?
A)
35.7 g N2H4
B)
24.0 g N2H4
C)
30.0 g N2H4
D)
29.2 g N2H4
E)
28.9 g N2H4
119. Nitric oxide, NO, is made from the oxidation of NH3, and the reaction is represented by the
equation:
4NH3 + 5O2 → 4NO + 6H2O
An 8.7-g sample of NH3 gives 12.0 g of NO. The percent yield of NO is
A)
73%
B)
63%
C)
41%
D)
78%
E)
20%
120. Ammonia can be made by reaction of water with magnesium nitride as shown by the
following unbalanced equation:
Mg3N2(s) + H2O(l) → Mg(OH)2(s) + NH3(g)
If this process is 80% efficient, what mass of ammonia can be prepared from 19.0 kg
magnesium nitride?
A)
2.6 kg NH3
B)
6.4 kg NH3
C)
5.1 kg NH3
D)
3.2 kg NH3
E)
15 kg NH3
121. Given the equation 3A + B → C + D, you react 1 mole of A with 3 moles of B.
True or false: A is the limiting reactant because you have fewer moles of A than B.
122. The reactant with the highest molar mass is always the limiting reactant.
123. The reactant which, when used up completely, can produce the least amount of product, is
the limiting reactant.
124. Naturally occurring iron contains 5.82% , 91.66% , 2.19% , and 0.33% .
The respective atomic masses are 53.940 amu, 55.935 amu, 56.935 amu, and 57.933 amu.
Calculate the average atomic mass of iron.
125. Vitamin B12, cyanocobalamin, is essential for human nutrition. It's concentrated in animal
tissue but not in higher plants. People who abstain completely from animal products may
develop anemia, so cyanocobalamin is used in vitamin supplements. It contains 4.35%
cobalt by mass. Calculate the molar mass of cyanocobalamin assuming there is one cobalt
per molecule.
126. Give the empirical formula for the following compounds:
a)
b)
c)
d)
127. The hormone epinephrine is released in the human body during stress and increases the
body's metabolic rate. Epinephrine, like many biochemical compounds, is composed of
carbon, hydrogen, oxygen, and nitrogen. The percentage composition of the hormone is
59.0% C, 7.15% H, 26.2% O, and 7.65% N. Determine the empirical formula.
128. The characteristic odor of pineapple is due to ethyl butanoate, a compound containing
carbon, hydrogen, and oxygen. Combustion of 2.78 g of ethyl butanoate leads to formation
of 6.32 g of CO2 and 2.58 g of H2O. The properties of the compound suggest that the molar
mass should be between 100 and 150 g/mol. What is the molecular formula?
129. In order to determine the molecular formula from the empirical formula, we must know the
__________.
130. In a chemical equation, the _________ are written on the left side of the arrow, and the
_________ are written on the right side of the arrow.
131. The __________ in a chemical equation represent the number of atoms in a particular
molecule or formula unit.
132. The __________ in a balanced equation represent numbers of molecules.
133. One of the major commercial uses of sulfuric acid is in the production of phosphoric acid
and calcium sulfate. The phosphoric acid is used for fertilizer. The reaction is
Ca3(PO4)2 + 3H2SO4 → 3CaSO4 + 2H3PO4. What mass of concentrated H2SO4 (98% by
mass) must be used to react completely with 100.00 g of calcium phosphate?
134. In a metallurgical process the mineral pyrite, FeS2, is roasted in air:
FeS2 + O2 → Fe2O3 + SO2
The SO2 is then converted into H2SO4 in the following reactions:
2SO2 + O2 → 2SO3
SO3 + H2SO4 → H2S2O7
H2S2O7 + H2O → 2H2SO4
Assuming the mineral is 24.0% FeS2 and the remainder is inert, what mass of H2SO4 is
produced if 155 g of the mineral is used?
of substances MSC: Quantitative
135. The percent yield is a ratio of the ____________ yield to the _____________ yield,
multiplied by 100%.
