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Sample Test
|
Chapter_03_Stoichiometry
1. Bromine exists naturally as a mixture of bromine-79
and bromine-81 isotopes. An atom of bromine-79 contains
|
|
a.
|
79 protons, 79 electrons, and 35 neutrons.
|
|
|
b.
|
35 protons, 44 neutrons, and 35 electrons.
|
|
|
c.
|
44 protons, 44 electrons, and 35 neutrons.
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|
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d.
|
34 protons and 35 electrons only.
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|
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e.
|
35 protons, 79 neutrons, and 35 electrons.
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.1
|
|
KEYWORDS:
|
atomic theory of matter | early atomic theory | general
chemistry | isotope
|
|
|
2. The atomic mass of rhenium is
186.2. Given that 37.1% of natural rhenium is rhenium-185, what is the other
stable isotope?
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.1
|
|
KEYWORDS:
|
atomic theory of matter | early atomic theory | general
chemistry | isotope
|
|
|
3. Consider the new element
moonium, atomic number 118, atomic mass 273.2 g. The nucleus of an atom of
moonium-273 contains
|
|
a.
|
118 protons, 118 alpha particles.
|
|
|
b.
|
118 protons, 155 neutrons.
|
|
|
c.
|
118 protons, 273neutrons.
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|
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d.
|
118protons, 155 neutrons, 118 electrons.
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|
|
e.
|
118protons, 118neutrons.
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.1
|
|
KEYWORDS:
|
atomic theory of matter | early atomic theory | general
chemistry | nuclear structure
|
|
|
4. For a new element, 60.54% is an
isotope with mass 282.1 amu, 3.28% is an isotope with mass 283.2 amu,
and 36.18% is an isotope with mass 284.6 amu. Calculate the
average atomic mass of this new element.
|
|
a.
|
283.3 amu
|
|
|
b.
|
849.9 amu
|
|
|
c.
|
282.1 amu
|
|
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d.
|
283.0 amu
|
|
|
e.
|
314.5 amu
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.1
|
|
KEYWORDS:
|
atomic theory of matter | atomic weight | early atomic
theory | general chemistry | relative atomic mass
|
|
|
5. The average mass of a boron
atom is 10.81. If you were able to isolate a single boron atom,
what is the chance that you would randomly get an atom with mass 10.81?
|
|
a.
|
greater than 50%
|
|
|
b.
|
0%
|
|
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c.
|
0.81%
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|
|
d.
|
10.81%
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|
|
e.
|
about 11%
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.1
|
|
KEYWORDS:
|
atomic theory of matter | atomic weight | early atomic
theory | general chemistry | relative atomic mass
|
|
|
6. Indium has atomic number 49 and
atomic mass 114.8 g. Naturally occurring indium contains a mixture
of indium-112 and indium-115 in an atomic ratio of approximately
|
|
a.
|
75/25.
|
|
|
b.
|
25/75.
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|
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c.
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6/94.
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|
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d.
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50/50.
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|
|
e.
|
94/6.
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|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.1
|
|
KEYWORDS:
|
atomic theory of matter | early atomic theory | general
chemistry | isotope
|
|
|
7. Boron naturally occurs in two
isotopic forms. The more common isotope is 11B (atomic mass 11.01 amu), which
is 80.00% abundant. The average atomic mass of boron is
10.81. What is the mass of the other isotope?
|
|
a.
|
10.91 amu.
|
|
|
b.
|
10.01 amu.
|
|
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c.
|
10.81 amu.
|
|
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d.
|
11.00 amu.
|
|
|
e.
|
11.01 amu.
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.1
|
|
KEYWORDS:
|
atomic theory of matter | atomic weight | early atomic
theory | general chemistry | relative atomic mass
|
|
|
8. A sample of iron weighing
15.0 g contains how many moles of iron atoms?
|
|
a.
|
3.72 mol
|
|
|
b.
|
0.269 mol
|
|
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c.
|
0.118 mol
|
|
|
d.
|
0.577 mol
|
|
|
e.
|
0.0780 mol
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.2
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
9. A single atom of an element weighs
5.81 × 10–23 g. Identify the isotope.
|
|
a.
|
35Cl
|
|
|
b.
|
103Rh
|
|
|
c.
|
80Br
|
|
|
d.
|
45Sc
|
|
|
e.
|
none of these
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.2
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
10. Iron is biologically important
in the transport of oxygen by red blood cells from the lungs to the various
organs of the body. In the blood of an adult human, there are approximately
2.60 × 1013 red blood cells with a total of 2.90 g of iron. On the
average, how many iron atoms are present in each red blood cell? (molar mass
for Fe = 55.85 g)
|
|
a.
|
8.33 × 10–10
|
|
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b.
|
1.20 × 109
|
|
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c.
|
5.19 × 10–2
|
|
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d.
|
3.12 × 1022
|
|
|
e.
|
2.60 × 1013
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.2
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
11. An alkali metal oxide contains
83.01% metal by mass. Determine the identity of the metal.
|
|
a.
|
Cs
|
|
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b.
|
Li
|
|
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c.
|
K
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|
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d.
|
Na
|
|
|
e.
|
Rb
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.2
3.3
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry | mass
percentage | stoichiometry
|
|
|
12. What is the molar mass of
ethanol (C2H5OH)?
|
|
a.
|
46.07
|
|
|
b.
|
62.07
|
|
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c.
|
45.07
|
|
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d.
|
38.90
|
|
|
e.
|
34.17
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance |
molecular weight | stoichiometry
|
|
|
13. For which of the following
compounds does 1.0 g represent 2.27 × 10–2 mol?
|
|
a.
|
H2O
|
|
|
b.
|
C2H6
|
|
|
c.
|
NH3
|
|
|
d.
|
CO2
|
|
|
e.
|
CO
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance |
molecular weight | stoichiometry
|
|
|
14. Which compound has the
smallest molar mass?
|
|
a.
|
C2H6
|
|
|
b.
|
CH3Cl
|
|
|
c.
|
CO2
|
|
|
d.
|
C2H4O
|
|
|
e.
|
none of these
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance |
molecular weight | stoichiometry
|
|
|
15. For which compound does 0.256
mole weigh 12.9 g?
|
|
a.
|
C2H4O2
|
|
|
b.
|
C2H6
|
|
|
c.
|
CH3Cl
|
|
|
d.
|
CO2
|
|
|
e.
|
C2H4O
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance |
molecular weight | stoichiometry
|
|
|
16. Calculate the molar mass of a
sample if a single molecule weighs 5.34 × 10–23 g.
|
|
a.
|
12.0 g/mol
|
|
|
b.
|
5.34 × 10–23 g/mol
|
|
|
c.
|
1.13 × 1046 g/mol
|
|
|
d.
|
32.2 g/mol
|
|
|
e.
|
none of these
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance |
molecular weight | stoichiometry
|
|
|
17. How many moles of P4 molecules molecules
are in 145.2 g of phosphorus?
|
|
a.
|
1.172 mol
|
|
|
b.
|
1.452 × 101 mol
|
|
|
c.
|
4.688 mol
|
|
|
d.
|
2.411 × 101 mol
|
|
|
e.
|
1.799 × 104 mol
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
18. What is the mass (in grams) of
one molecule of phosphorus pentachloride?
|
|
a.
|
1.25 × 1026 g
|
|
|
b.
|
3.46 × 10–22 g
|
|
|
c.
|
1.10 × 10–22 g
|
|
|
d.
|
208.22 g
|
|
|
e.
|
1.00 g
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
19. How many molecules of ammonia
are present in 6.9 g of ammonia?
|
|
a.
|
6.7 × 10–25
|
|
|
b.
|
4.1 × 101
|
|
|
c.
|
8.3 × 1023
|
|
|
d.
|
4.2 × 1024
|
|
|
e.
|
2.4 × 1023
|
|
ANSWER:
|
e
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
20. How many atoms of hydrogen are
present in 4.0 g of ammonia?
|
|
a.
|
7.8 × 1024
|
|
|
b.
|
0.70
|
|
|
c.
|
4.2 × 1023
|
|
|
d.
|
1.2 × 10–24
|
|
|
e.
|
1.8 × 1024
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
21. The mass of 0.82 mol of a
diatomic molecule is 131.3 g. Identify the molecule.
|
|
a.
|
Xe
|
|
|
b.
|
Cl2
|
|
|
c.
|
I2
|
|
|
d.
|
F2
|
|
|
e.
|
Br2
|
|
ANSWER:
|
e
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance |
molecular weight | stoichiometry
|
|
|
22. Roundup, an herbicide
manufactured by Monsanto, has the formula C3H8NO5P. How many moles of
molecules are there in a 500.-g sample of Roundup?
|
|
a.
|
84.5
|
|
|
b.
|
2.96
|
|
|
c.
|
0.338
|
|
|
d.
|
1.75
|
|
|
e.
|
none of these
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
23. What mass of styrene (molar
mass 104.1 g/mol) contains 4.50 × 1020 molecules of styrene?
|
|
a.
|
7.78 × 10–2 g
|
|
|
b.
|
7.48 × 104 g
|
|
|
c.
|
0.00778 g
|
|
|
d.
|
7.48 × 10–4 g
|
|
|
e.
|
7.48 × 10–3 g
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
24. Phosphorus has the molecular
formula P4 and sulfur has the molecular formula S8. How many grams of
phosphorus contain the same number of molecules as 6.41 g of sulfur?
|
|
a.
|
6.19 g
|
|
|
b.
|
6.41 g
|
|
|
c.
|
3.21 g
|
|
|
d.
|
3.10 g
|
|
|
e.
|
none of these
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
25. The molar mass of the
insecticide dibromoethane is 187.9 g/mol. Its molecular formula is
C2H4Br2. How many atoms
of carbon are in a sample of dibromoethane weighing 1.879 g?
|
|
a.
|
none of these
|
|
|
b.
|
1.204 × 1022
|
|
|
c.
|
6.022 × 100.21
|
|
|
d.
|
6.022 × 1021
|
|
|
e.
|
12.04 × 1044
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
26. A given sample of xenon
fluoride contains molecules of a single type, XeFn, where n is some whole
number. Given that 9.03 × 1020 molecules of XeFn weigh 0.311 g, calculate n.
|
|
a.
|
2
|
|
|
b.
|
4
|
|
|
c.
|
1
|
|
|
d.
|
none of these
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
determining chemical formulas | empirical formula |
general chemistry | stoichiometry
|
|
|
27. NaHCO3 is the active
ingredient in baking soda. How many grams of oxygen are in 0.36 g of
NaHCO3?
|
|
a.
|
0.0043 g
|
|
|
b.
|
0.21 g
|
|
|
c.
|
0.013g
|
|
|
d.
|
0.069 g
|
|
|
e.
|
1.1 g
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
28. The empirical formula of sugar
is CH2O
and its molar mass is 180.2 g/mole. If one teaspoon of sugar
weighs 3.50 g, how many moles of sugar and how many molecules of sugar are
present?
|
|
a.
|
0.0194 mole, 3.24 × 1026 molecules
|
|
|
b.
|
0.0295 mole, 1.78 × 1022 molecules
|
|
|
c.
|
0.0583 mole, 3.51 × 1022 molecules
|
|
|
d.
|
0.0194 mole, 1.17 × 1022 molecules
|
|
|
e.
|
0.117 mole, 7.03 × 1022 molecules
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
29. Compound X2Y is 60% X by
mass. Calculate the percent Y by mass of the compound X2Y2.
|
|
a.
|
30%
|
|
|
b.
|
80%
|
|
|
c.
|
40%
|
|
|
d.
|
20%
|
|
|
e.
|
60%
|
|
ANSWER:
|
e
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
3.4
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry | mass
percentage | stoichiometry
|
|
|
30. Cortisone consists of
molecules, each of which contains 21 atoms of carbon (plus other atoms). The
mass percentage of carbon in cortisone is 69.98%. What is the molar mass of
cortisone?
|
|
a.
|
287.6 g/mol
|
|
|
b.
|
360.4 g/mol
|
|
|
c.
|
176.5 g/mol
|
|
|
d.
|
252.2 g/mol
|
|
|
e.
|
312.8 g/mol
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
3.5
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance |
molecular weight | stoichiometry
|
|
|
31. An oxybromate compound, NaBrOx, where x is a whole
number, is analyzed and found to contain 52.95% Br by mass. What
is x?
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.3
3.5
|
|
KEYWORDS:
|
determining chemical formulas | empirical formula |
general chemistry | stoichiometry
|
|
|
32. Which of the following
contains the greatest percentage of nitrogen by mass?
|
|
a.
|
NH3
|
|
|
b.
|
HCN
|
|
|
c.
|
C6H4N3O6
|
|
|
d.
|
N2O
|
|
|
e.
|
NO2
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.4
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry | mass
percentage | stoichiometry
|
|
|
33. The molar mass of the insecticide
dibromoethane is 187.9. Its molecular formula is C2H4Br2. What percent by mass of
bromine does dibromoethane contain?
|
|
a.
|
50.0%
|
|
|
b.
|
37.8%
|
|
|
c.
|
42.5%
|
|
|
d.
|
89.3%
|
|
|
e.
|
85.0%
|
|
ANSWER:
|
e
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.4
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry | mass
percentage | stoichiometry
|
|
|
34. A substance contains 3.024 g
hydrogen, 30.97 g phosphorus, and 64.00 g oxygen. How many grams
of oxygen are in an 85.00-g sample of the substance?
|
|
a.
|
64.00 g
|
|
|
b.
|
130.1 g
|
|
|
c.
|
16.00 g
|
|
|
d.
|
55.51 g
|
|
|
e.
|
none of these
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.4
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry | mass
percentage | stoichiometry
|
|
|
35. What is the percent by mass of
hydrogen in ammonium acetate?
|
|
a.
|
7.07%
|
|
|
b.
|
5.23%
|
|
|
c.
|
14.3%
|
|
|
d.
|
3.92%
|
|
|
e.
|
9.15%
|
|
ANSWER:
|
e
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.4
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mass
percentage | stoichiometry
|
|
|
36. A hydrate of copper(II)
sulfate is 25.5% copper by mass. How many water molecules are
there for each unit of copper(II) sulfate?
|
ANSWER:
|
e
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.4
|
|
KEYWORDS:
|
determining chemical formulas | empirical formula |
general chemistry | stoichiometry
|
|
|
37. Which of the following
compounds has the same percent composition by mass as styrene, C8H8?
|
|
a.
|
cyclobutadiene, C4H4
|
|
|
b.
|
α-ethyl naphthalene, C12H12
|
|
|
c.
|
acetylene, C2H2
|
|
|
d.
|
benzene, C6H6
|
|
|
e.
|
all of these
|
|
ANSWER:
|
e
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.4
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry | mass
percentage | stoichiometry
|
|
|
38. Find the percent sulfur
(atoms) by mass in sodium sulfide.
|
|
a.
|
52.1%
|
|
|
b.
|
58.2%
|
|
|
c.
|
41.1%
|
|
|
d.
|
74.4%
|
|
|
e.
|
73.6%
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.4
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry | mass
percentage | stoichiometry
|
|
|
39. You find a compound composed
only of element X and hydrogen, and you know that it is 91.33% element X by
mass. Each molecule has 2.67 times as many H atoms as X
atoms. What is element X?
|
|
a.
|
Cu
|
|
|
b.
|
Si
|
|
|
c.
|
Cl
|
|
|
d.
|
C
|
|
|
e.
|
Ne
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.4
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mole |
mole calculations | stoichiometry
|
|
|
40. A mixture of NaCl and NaNO3 is 31.7% sodium by
mass. What is the approximate percent of NaCl in this mixture?
|
|
a.
|
32%
|
|
|
b.
|
30%
|
|
|
c.
|
38%
|
|
|
d.
|
36%
|
|
|
e.
|
34%
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.4
|
|
KEYWORDS:
|
general chemistry | mass and moles of substance | mass
percentage | stoichiometry
|
|
|
41. TNT consists of carbon,
nitrogen, oxygen, and hydrogen. It is 37.02% carbon by mass,
18.49% nitrogen by mass, and 42.27% oxygen by mass. The molar mass
of TNT is between 210 g/mol and 245 g/mol. What is the molecular
formula for TNT?
|
|
a.
|
C4H7N6O6
|
|
|
b.
|
C6H4N3O6
|
|
|
c.
|
C7H5N3O6
|
|
|
d.
|
C8H12N3O4
|
|
|
e.
|
none of these
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.4
3.5
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry |
molecular formula | stoichiometry
|
|
|
42. Caffeine consists of carbon,
hydrogen, oxygen, and nitrogen. When 0.1920 g of caffeine is
burned in an excess of oxygen, 0.3482 g of carbon dioxide and 0.0891 g water
are formed. Caffeine is 28.84% nitrogen by mass. Its
molar mass is between 190 and 200 g/mol. What is the formula for
caffeine?
|
|
a.
|
C6H4N4O4
|
|
|
b.
|
C8H10N4O2
|
|
|
c.
|
C4H5N2O
|
|
|
d.
|
C3H2N2O2
|
|
|
e.
|
none of these
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.4
3.5
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry |
molecular formula | stoichiometry
|
|
|
43. The empirical formula of a
group of compounds is CHCl. Lindane, a powerful insecticide, is a member of
this group. The molar mass of lindane is 290.8. How many atoms of carbon does
a molecule of lindane contain?
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.5
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry |
molecular formula | stoichiometry
|
|
|
44. The empirical formula of
styrene is CH; its molar mass is 104.1. What is the molecular formula of
styrene?
|
|
a.
|
C2H4
|
|
|
b.
|
C8H8
|
|
|
c.
|
C6H6
|
|
|
d.
|
C10H12
|
|
|
e.
|
none of these
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.5
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry |
molecular formula | stoichiometry
|
|
|
45. What is the empirical formula
of a hydrocarbon (a compound that consists of only carbon and hydrogen) that
contains 81.7% carbon by mass?
|
|
a.
|
C5H12
|
|
|
b.
|
C3H8
|
|
|
c.
|
C4H10
|
|
|
d.
|
C2H6
|
|
|
e.
|
none of these
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.5
|
|
KEYWORDS:
|
determining chemical formulas | empirical formula |
general chemistry | stoichiometry
|
|
|
46. The mass percent of iron in an
iron oxide is 77.7%. Find the empirical formula.
|
|
a.
|
Fe3O2
|
|
|
b.
|
Fe3O4
|
|
|
c.
|
Fe2O3
|
|
|
d.
|
FeO
|
|
|
e.
|
none of these
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.5
|
|
KEYWORDS:
|
determining chemical formulas | empirical formula | general
chemistry | stoichiometry
|
|
|
47. Adipic acid contains 49.32% C,
43.84% O, and 6.85% H by mass. What is the empirical formula?
|
|
a.
|
C2H5O4
|
|
|
b.
|
C3H5O2
|
|
|
c.
|
C2HO3
|
|
|
d.
|
C3H3O4
|
|
|
e.
|
C3HO3
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.5
|
|
KEYWORDS:
|
determining chemical formulas | empirical formula |
general chemistry | stoichiometry
|
|
|
48. Vitamin C contains the
elements C, H, and O. It is known to contain 40.9% C and 4.58% H by mass. The
molar mass of vitamin C has been found to be about 180. The molecular formula
for vitamin C is
|
|
a.
|
C6H8O6
|
|
|
b.
|
C4H6O4
|
|
|
c.
|
C3H4O3
|
|
|
d.
|
C2H3O2
|
|
|
e.
|
none of these
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.5
|
|
KEYWORDS:
|
determining chemical formulas | general chemistry |
molecular formula | stoichiometry
|
|
|
49. A 2.00-g sample of an oxide of
bromine is converted to 2.936 g of AgBr. Calculate the empirical
formula of the oxide. (molar mass for AgBr = 187.78)
|
|
a.
|
BrO3
|
|
|
b.
|
BrO
|
|
|
c.
|
BrO2
|
|
|
d.
|
Br2O
|
|
|
e.
|
none of these
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.5
|
|
KEYWORDS:
|
determining chemical formulas | empirical formula |
general chemistry | stoichiometry
|
|
|
50. A 0.4647-g sample of a
compound known to contain only carbon, hydrogen, and oxygen was burned in
oxygen to yield 0.8635 g of CO2 and 0.1767 g of H2O. What is the empirical formula of the compound?
|
|
a.
|
C3H3O2
|
|
|
b.
|
C2H2O
|
|
|
c.
|
C6H3O2
|
|
|
d.
|
C3H6O2
|
|
|
e.
|
CHO
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.5
|
|
KEYWORDS:
|
determining chemical formulas | empirical formula |
general chemistry | stoichiometry
|
|
|
51. When the equation C6H14 + O2 → CO2 + H2O is balanced with the
smallest set of integers, the sum of the coefficients is
|
|
a.
|
28
|
|
|
b.
|
33
|
|
|
c.
|
47
|
|
|
d.
|
4
|
|
|
e.
|
40
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.6
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | early
atomic theory | general chemistry
|
|
|
52. Consider the following
unbalanced equation:
C4H10 + O2 → CO2 +
H2O
For every 1.0 mol of C4H10,
___ mol of O2 is required.
|
|
a.
|
1.0
|
|
|
b.
|
8.0
|
|
|
c.
|
13.0
|
|
|
d.
|
6.5
|
|
|
e.
|
none of these
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | early
atomic theory | general chemistry
|
|
|
53. wPCl5 + xH2O → yPOCl3 + zHCl
When the equation is properly balanced, what are the
coefficients?
|
|
a.
|
w = 1, x = 1, y = 1, z = 2
|
|
|
b.
|
w = 2, x = 2, y = 2, z = 2
|
|
|
c.
|
w = 1, x = 2, y = 2, z = 4
|
|
|
d.
|
w = 2, x = 2, y = 2, z = 4
|
|
|
e.
|
none of these
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | early
atomic theory | general chemistry
|
|
|
54. What is the subscript of
aluminum in the formula of aluminum phosphate?
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
chemical formula | chemical substance | early atomic
theory | general chemistry | ionic substance
|
|
|
55. Give (in order) the correct
coefficients to balance the following reaction:
H2SnCl6 + H2S →
SnS2 + HCl
|
|
a.
|
1, 2, 2, 2
|
|
|
b.
|
1, 2, 1, 6
|
|
|
c.
|
1, 1, 1, 6
|
|
|
d.
|
6, 2, 1, 1
|
|
|
e.
|
2, 4, 2, 6
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | early
atomic theory | general chemistry
|
|
|
56. In the balanced equation for
the reaction
[A]P4O6(s) + [B]H2O(l) → [C]H3PO3(aq)
if [A] equals 2, the coefficient [C] equals
|
|
a.
|
6
|
|
|
b.
|
4
|
|
|
c.
|
2
|
|
|
d.
|
10
|
|
|
e.
|
none of these
|
|
ANSWER:
|
e
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | general
chemistry | stoichiometry
|
|
|
57. Which of the following
equations correctly describes the combustion of CH4 and O2 to produce water (H2O) and carbon dioxide (CO2)?
|
|
a.
|
CH4 +
(1/2)O2 →
CO2 +
H2O
|
|
|
b.
|
CH4 +
2O2 →
CO2 +
2H2O
|
|
|
c.
|
CH4 +
3O2 →
2CO2 +
H2O
|
|
|
d.
|
CH4 +
O2 →
CO2 +
2H2O
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
chemical equation | early atomic theory | general
chemistry | writing equation
|
|
|
58. When the following equation is
balanced, what is the sum of the coefficients?
Al2(SO4)3 + Ca(OH)2 →
Al(OH)3 + CaSO4
|
|
a.
|
10
|
|
|
b.
|
8
|
|
|
c.
|
4
|
|
|
d.
|
9
|
|
|
e.
|
3
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | early
atomic theory | general chemistry
|
|
|
59. When the equation FeCr2O4 + K2CO3 + O2 → K2CrO4 + Fe2O3 + CO2 is balanced with the
smallest set of integers, the sum of the coefficients is
|
|
a.
|
9
|
|
|
b.
|
15
|
|
|
c.
|
6
|
|
|
d.
|
37
|
|
|
e.
|
24
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | early
atomic theory | general chemistry
|
|
|
60. Potassium forms an oxide
containing 1 oxygen atom for every 2 atoms of potassium. What is the coefficient
of oxygen in the balanced equation for the reaction of potassium with oxygen
to form this oxide?
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | early
atomic theory | general chemistry
|
|
|
61. How many moles of sodium
phosphate are required to react completely with 3.0 mol of calcium
nitrate to form sodium nitrate and calcium phosphate?
|
|
a.
|
2.0 mol
|
|
|
b.
|
3.0 mol
|
|
|
c.
|
1.0 mol
|
|
|
d.
|
1.5 mol
|
|
|
e.
|
4.5 mol
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
general chemistry | molar interpretation | stoichiometry
| stoichiometry calculation
|
|
|
62. When the equation NH3 + O2 → NO + H2O is balanced with the
smallest set of integers, the sum of the coefficients is
|
|
a.
|
4
|
|
|
b.
|
24
|
|
|
c.
|
12
|
|
|
d.
|
14
|
|
|
e.
|
19
|
|
ANSWER:
|
e
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
general chemistry | molar interpretation | stoichiometry
| stoichiometry calculation
|
|
|
63. Indium reacts with chlorine to
form InCl3. In the balanced equation for this reaction, the coefficient
of the indium trichloride is
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | early
atomic theory | general chemistry
|
|
|
64. Consider the following
unbalanced equation:
KO2 + H2O → KOH + O2 +
H2O2
For every 3.0 mol of KO2,
___ mol of H2O is needed for a complete reaction.
|
|
a.
|
6.0
|
|
|
b.
|
2.0
|
|
|
c.
|
3.0
|
|
|
d.
|
1.0
|
|
|
e.
|
none of these
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
general chemistry | molar interpretation | stoichiometry
| stoichiometry calculation
|
|
|
65. Baking powder, a mixture of
cream of tartar (KHC4H4O6, molar mass 188 g/mol) and baking soda (NaHCO3, molar mass 84.0 g/mol),
undergoes the following reaction at baking temperatures:
KHC4H4O6 + NaHCO3 → KNaC4H4O6 +
H2O + CO2
(The CO2 makes the cake
rise.) A recipe calls for two level teaspoons (a total of 8.0 g)
of cream of tartar. How much baking soda must be added for both
materials to react completely?
|
|
a.
|
8.0 g
|
|
|
b.
|
0.45 g
|
|
|
c.
|
3.6 g
|
|
|
d.
|
18 g
|
|
|
e.
|
none of these
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
amounts of substances | general chemistry |
stoichiometry | stoichiometry calculation
|
|
|
66. A reaction occurs between
sodium carbonate and hydrochloric acid producing sodium chloride, carbon
dioxide, and water. The correct set of coefficients, respectively, for the
balanced reaction is
|
|
a.
|
5, 10, 10, 5, 5.
|
|
|
b.
|
1, 2, 2, 1, 1.
|
|
|
c.
|
8, 6, 5, 10, 5.
|
|
|
d.
|
3, 6, 6, 3, 4.
|
|
|
e.
|
none of these
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.7
|
|
KEYWORDS:
|
balancing chemical equation | chemical equation | early
atomic theory | general chemistry
|
|
|
67. A 6.32-g sample of potassium
chlorate was decomposed according to the following equation:
2KClO3 → 2KCl + 3O2
How many moles of oxygen are formed?
|
|
a.
|
0.051 mol
|
|
|
b.
|
0.0774 mol
|
|
|
c.
|
0.0344 mol
|
|
|
d.
|
1.65 mol
|
|
|
e.
|
none of these
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.8
|
|
KEYWORDS:
|
amounts of substances | general chemistry |
stoichiometry | stoichiometry calculation
|
|
|
68. 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 form 5.00 mol of FeS2?
|
|
a.
|
12.2 mol
|
|
|
b.
|
20.0 mol
|
|
|
c.
|
6.11 mol
|
|
|
d.
|
10.0 mol
|
|
|
e.
|
5.00 mol
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.8
|
|
KEYWORDS:
|
general chemistry | molar interpretation | stoichiometry
| stoichiometry calculation
|
|
|
69. Consider the following
reaction:
CH4(g)
+ 4Cl2(g)
→ CCl4(g)
+ 4HCl(g)
What mass of CCl4 is
formed by the reaction of 8.00 g of methane with an excess of chlorine?
|
|
a.
|
14.2 g
|
|
|
b.
|
7.10 g
|
|
|
c.
|
76.7 g
|
|
|
d.
|
1.42 g
|
|
|
e.
|
none of these
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.8
|
|
KEYWORDS:
|
amounts of substances | general chemistry |
stoichiometry | stoichiometry calculation
|
|
|
70. When rubidium metal is exposed
to air, one atom of rubidium, Rb, combines with two atoms of oxygen. If 1.75
g of rubidium is exposed to air, what will be the mass of the product in
grams?
|
|
a.
|
0.655 g
|
|
|
b.
|
1.37 g
|
|
|
c.
|
0.328 g
|
|
|
d.
|
2.41 g
|
|
|
e.
|
2.08 g
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.8
|
|
KEYWORDS:
|
amounts of substances | general chemistry |
stoichiometry | stoichiometry calculation
|
|
|
71. Iron is produced from its ore
by the following reactions:
2C(s)
+ O2(g)
→ 2CO(g)
Fe2O3(s)
+ 3CO(g) →
2Fe(s) + 3CO2(g)
How many moles of C(s) are
needed to produce 2.4 mol Fe(s)?
|
|
a.
|
3.6 mol C
|
|
|
b.
|
2.4 mol C
|
|
|
c.
|
5.0 mol C
|
|
|
d.
|
1.6 mol C
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.8
|
|
KEYWORDS:
|
general chemistry | molar interpretation | stoichiometry
| stoichiometry calculation
|
|
|
72. Consider the following two
reactions.
|
Mg + 2HCl→ MgCl2 + H2
2H2 +
O2→ 2H2O
|
How much water (in grams) is produced from 10.0 g of Mg?
|
|
a.
|
3.71 g
|
|
|
b.
|
18.0 g
|
|
|
c.
|
7.41 g
|
|
|
d.
|
1.85 g
|
|
|
e.
|
none of these
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.8
|
|
KEYWORDS:
|
amounts of substances | general chemistry |
stoichiometry | stoichiometry calculation
|
|
|
73. 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.
|
1.9 × 1014 g
|
|
|
b.
|
7.6 × 1014 g
|
|
|
c.
|
1.3 × 1013 g
|
|
|
d.
|
5.3 × 1013 g
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.8
|
|
KEYWORDS:
|
amounts of substances | general chemistry |
stoichiometry | stoichiometry calculation
|
|
|
74. One commercial system removes
SO2 emissions
from smoke at 95.0°C by the following set of balanced reactions:
SO2(g)
+ Cl2 → SO2Cl2(g)
SO2Cl2 + 2H2O →
H2SO4 + 2HCl
H2SO4 + Ca(OH)2 →
CaSO4(s)
+ 2H2O
Assuming the process is 95.0% efficient, how many grams of
CaSO4 may be produced from 1.00 × 102 g
of SO2 (molar masses: SO2,
64.1 g/mol; CaSO4, 136 g/mol)?
|
|
a.
|
47.1 g
|
|
|
b.
|
212 g
|
|
|
c.
|
202 g
|
|
|
d.
|
87.2 g
|
|
|
e.
|
44.8 g
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.8
|
|
KEYWORDS:
|
amounts of substances | general chemistry |
stoichiometry | stoichiometry calculation
|
|
|
75. How many grams of Ca(NO3)2 can be produced by
reacting excess HNO3 with 7.40 g of Ca(OH)2?
|
|
a.
|
10.2 g
|
|
|
b.
|
16.4 g
|
|
|
c.
|
7.40 g
|
|
|
d.
|
8.22 g
|
|
|
e.
|
32.8 g
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.8
|
|
KEYWORDS:
|
amounts of substances | general chemistry |
stoichiometry | stoichiometry calculation
|
|
|
76. How many grams of H2O will be formed when
39.0 g H2 is mixed with 49.6 g O2 and allowed to
completely react to form water?
|
|
a.
|
88.6 g
|
|
|
b.
|
55.8 g
|
|
|
c.
|
27.9 g
|
|
|
d.
|
351 g
|
|
|
e.
|
59.1 g
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.8
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry | stoichiometry
calculation
|
|
|
77. The limiting reactant in a
reaction
|
|
a.
|
is the reactant for which you have the least number of
moles.
|
|
|
b.
|
has the lowest coefficient in a balanced equation.
|
|
|
c.
|
has the lowest ratio of coefficient in the balanced
equation to moles available.
|
|
|
d.
|
has the lowest ratio of moles available to coefficient
in the balanced equation.
|
|
|
e.
|
none of these
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
easy
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
78. 29.4 g of Al and 25.0g of Br2 react according to
the following equation:
2Al + 3Br2 → 2AlBr3
What mass of AlBr3 is
formed, assuming 100% yield?
|
|
a.
|
62.6 g
|
|
|
b.
|
291 g
|
|
|
c.
|
27.8 g
|
|
|
d.
|
54.4 g
|
|
|
e.
|
41.7 g
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
79. In the reaction
2A + 3B → C
4.0 mol A react with 4.0 mol B. Which reactant is
limiting?
|
|
a.
|
A is limiting because there are 2 mol of it but 4.0 mol
are needed.
|
|
|
b.
|
B is limiting because there are 4.0 mol of it but 6.0
mol are needed.
|
|
|
c.
|
A is limiting because 2 is smaller than 3 (the
coefficients in the balanced equation).
|
|
|
d.
|
Neither is limiting because equal amounts (4.0 mol) of
each reactant are used.
|
|
|
e.
|
B is limiting because 3 is larger than 2 (the
coefficients in the balanced equation).
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
80. A 7.66-g sample of AgNO3 is reacted with BaCl2 according to the
equation
2AgNO3(aq) + BaCl2(aq) → 2AgCl(s) + Ba(NO3)2(aq)
to give 4.34 g of AgCl. What is the percent yield of
AgCl?
|
|
a.
|
47.8%
|
|
|
b.
|
56.7%
|
|
|
c.
|
67.2%
|
|
|
d.
|
33.6%
|
|
|
e.
|
20.1%
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
amounts of substances | general chemistry | stoichiometry
| stoichiometry calculation
|
|
|
81. When 10.0 g of hydrogen gas
reacts with 10.0 g of oxygen gas to form water, what is the theoretical yield
of water?
|
|
a.
|
10.6 g
|
|
|
b.
|
20.0 g
|
|
|
c.
|
11.3 g
|
|
|
d.
|
10.0 g
|
|
|
e.
|
89.4 g
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
82. Consider the following
reaction:
CH4(g)
+ 4Cl2(g)
→ CCl4(g)
+ 4HCl(g)
What mass of CCl4 will
be formed if 1.4moles of methane react with 1.4 moles of chlorine?
|
|
a.
|
861 g
|
|
|
b.
|
215 g
|
|
|
c.
|
51.0 g
|
|
|
d.
|
53.8 g
|
|
|
e.
|
21.5 g
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
83. In the 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.
|
89%
|
|
|
c.
|
100%
|
|
|
d.
|
75%
|
|
|
e.
|
67%
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
moderate
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
84. 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 is formed.
|
|
|
b.
|
1.13 g of H2S remains.
|
|
|
c.
|
0.0216 mol of H2S remains.
|
|
|
d.
|
10.6 g of sulfur is formed.
|
|
|
e.
|
SO2 is
the limiting reagent.
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
85. 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 mol lithium fluoride and 0.395 mol fluorine
|
|
|
b.
|
0.789 mol lithium fluoride and 1.37 mol lithium
|
|
|
c.
|
0.789 mol lithium fluoride only
|
|
|
d.
|
2.16 mol lithium fluoride only
|
|
|
e.
|
none of these
|
|
ANSWER:
|
b
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
86. Consider the electrolysis of a
brine solution:
2NaCl(aq)
+ H2O → Cl2(g) + H2(g) + 2NaOH(aq)
A 10.0-g sample of sodium chloride was placed in 10.0 g of
water. If 3.85 g of Cl2 was obtained,
what was the percent yield of Cl2?
|
|
a.
|
95.8%
|
|
|
b.
|
38.5%
|
|
|
c.
|
19.3%
|
|
|
d.
|
63.5%
|
|
|
e.
|
19.6%
|
|
ANSWER:
|
d
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
87. Consider the following
balanced equation:
A(g)
+ 5B(g) → 3C
+ 4D
When equal masses of A and B are reacted, which is limiting?
|
|
a.
|
If the molar mass of A is less than the molar mass of B,
then B must be limiting.
|
|
|
b.
|
If the molar mass of A is greater than the molar mass of
B, then B must be limiting.
|
|
|
c.
|
If the molar mass of A is less than the molar mass of B,
then A must be limiting.
|
|
|
d.
|
If the molar mass of A is greater than the molar mass of
B, then A must be limiting.
|
|
|
e.
|
More information is needed.
|
|
ANSWER:
|
a
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | limiting reactant | stoichiometry |
stoichiometry calculation
|
|
|
88. Consider the following
reaction:
4NH3(g)
+ 7O2(g)
→ 4NO2(g)
+ 6H2O(l)
Consider an experiment in which you react ammonia and
oxygen. At the end of the experiment, you find that you produced
27.0 g of water, and 8.52 g of ammonia is left over. Calculate the
initial mass of ammonia. Assume the reaction went to completion.
|
|
a.
|
34.1 g
|
|
|
b.
|
17.0 g
|
|
|
c.
|
25.5 g
|
|
|
d.
|
68.0 g
|
|
|
e.
|
10.8 g
|
|
ANSWER:
|
c
|
|
POINTS:
|
1
|
|
DIFFICULTY:
|
difficult
|
|
TOPICS:
|
3.9
|
|
KEYWORDS:
|
general chemistry | molar interpretation | stoichiometry
| stoichiometry calculation
|
|
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