Princeton 2012/Barron 4th ed.
AP Practice Problems
Unit 5 – Compounds & Moles
Multiple Choice (no calculator)
For questions 1-2, one or more of the
following responses will apply; each
response may be used more than once or not
at all in these questions.
A.
B.
C.
D.
E.
Moles
Liters
Grams
Atmospheres
Volts
1. One mole of solid zinc has a mass of
65.39 of these. (P5.1)
2. These units can be calculated by
dividing a quantity by 6.02×1023.
(P5.2)
3. What is the mass ratio of fluorine to
boron in a boron trifluoride
molecule? (P5.4)
a.
b.
c.
d.
e.
1.8 to 1
3.0 to 1
3.5 to 1
5.3 to 1
6.0 to 1
4. What is the mass of oxygen in 148
grams of calcium hydroxide
(Ca(OH)2)? (P5.6)
a.
b.
c.
d.
e.
16 grams
24 grams
32 grams
48 grams
64 grams
5. An ion containing only oxygen and
chlorine is 31% oxygen by mass.
What is its empirical formula? (P5.7)
a.
b.
c.
d.
e.
ClOClO2ClO3ClO4Cl2O-
6. What is the percent composition by
mass of the elements in the
compound NaNO3? (P5.9)
a.
b.
c.
d.
e.
Na 20%, N 20%, O 60%
Na 23%, N 14%, O 48%
Na 23%, N 14%, O 63%
Na 27%, N 16%, O 57%
Na 36%, N 28%, O 36%
7. The composition of a typical glass
used in bottles is 12.0% Na2O,
12.0% CaO, and 76% SiO2. Which
of the following lists the three
compounds in order of greatest to
least number of moles present in a
typical sample of bottle glass?
(P5.11)
a.
b.
c.
d.
e.
SiO2, CaO, Na2O
SiO2, Na2O, CaO
Na2O, SiO2, CaO
Na2O, CaO, SiO2
CaO, Na2O, SiO2
Princeton 2012/Barron 4th ed.
8. The concentration of sodium
chloride in sea water is about 0.5
molar. How many grams of NaCl
are present in 1 kg of sea water?
(P5.12)
a.
b.
c.
d.
e.
30 grams
60 grams
100 grams
300 grams
600 grams
9. A sample of a hydrate of CuSO4 with
a mass of 250 grams was heated until
all the water was removed. The
sample was then weighed and found
to have a mass of 160 grams. What
is the formula for the hydrate?
(P5.13)
a.
b.
c.
d.
e.
CuSO4  10 H2O
CuSO4  7 H2O
CuSO4  5 H2O
CuSO4  2 H2O
CuSO4  H2O
10. A compound containing only sulfur
and oxygen is 50% sulfur by weight.
What is the empirical formula for the
compound? (P5.14)
a.
b.
c.
d.
e.
SO
SO2
SO3
S2O
S3O
11. A sample of a hydrate of BaCl2 with
a mass of 61 grams was heated until
all the water was removed. The
sample was then weighed and found
to have a mass of 52 grams. What is
the formula for the hydrate? (P5.21)
a.
b.
c.
d.
e.
BaCl2  5 H2O
BaCl2  4 H2O
BaCl2  3 H2O
BaCl2  2 H2O
BaCl2  H2O
12. A hydrocarbon was found to be 20%
hydrogen by weight. If 1 mole of the
hydrocarbon has a mass of 30 grams,
what is its molecular formula?
(P5.22)
a.
b.
c.
d.
e.
CH
CH2
CH3
C2H4
C2H6
13. A hydrocarbon contains 75% carbon
by mass. What is the empirical
formula for the compound? (P5.24)
a.
b.
c.
d.
e.
CH2
CH3
CH4
C2H5
C3H8
14. When chlorine gas is combined with
fluorine gas, a compound is formed
that is 38% chlorine and 62%
fluorine. What is the empirical
formula of the compound? (P5.25)
a.
b.
c.
d.
e.
ClF
ClF2
ClF3
ClF5
ClF7
Princeton 2012/Barron 4th ed.
For questions 16-18, one or more of the
following responses will apply; each
response may be used more than once or not
at all in these questions.
I.
II.
III.
IV.
V.
ammonium ion
calcium ion
bromide ion
iron (III)
phosphate ion
15. Which of these carries a single
negative charge? (B4.1)
a.
b.
c.
d.
e.
I
II
III
IV
V
16. Which pair of these will form a
compound? (B4.2)
a.
b.
c.
d.
e.
I and II
II and IV
III and V
I and IV
II and V
17. How many different compounds can
be made from these ions? (B4.3)
a.
b.
c.
d.
e.
1
2
4
6
9
18. Which of the following is the
permanganate ion? (B4.7)
a. ClO4b. PO4-3
c. MnO2
d. SO4-2
e. MnO4-
19. The correct name for Fe(NO3)3 is
(B4.9)
a.
b.
c.
d.
e.
Iron nitrite
Iron (II) nitrate
Ferrous nitroxide
Iron (III) sulfate
Iron (III) nitrate
20. What is the formula for an ionic
compound formed from aluminum
and chlorine? (B4.13)
a.
b.
c.
d.
e.
AlCl
Al3Cl
Al3Cl3
AlCl3
Al2Cl3
21. Which of the following is NOT
correctly named? (B4.15)
a. Clchloride ion
b. ClO- hypochlorite ion
c. ClO4- perchlorate ion
d. ClO2- chlorous ion
e. ClO3- chlorate ion
22. Which of the following is NOT a
correct chemical formula? (B4.16)
a.
b.
c.
d.
e.
SrBr2
Ca2O3
Mg3N2
Na2S
AlI3
23. Which of the following is a correct
formula? (B4.17)
a.
b.
c.
d.
e.
NH4SO3
CaC2H3O2
Na2ClO4
Ba(CO3)2
KH2PO4
Princeton 2012/Barron 4th ed.
For questions 24-26, one or more of the
following responses will apply; each
response may be used more than once or not
at all in these questions.
I.
II.
III.
IV.
V.
molarity
mass percentage
molar mass
empirical formula
molecular formula
24. For the compound FeCl3 we can,
with the aid only of a periodic table
determine its (B6.1)
a.
b.
c.
d.
e.
I and III
II
III and V
II, III, and IV
V
25. We can determine the ______ if we
know the _______. (B6.3)
a.
b.
c.
d.
e.
I, III
II, III
III, V
IV, II
V, I
26. We can determine the ______ if we
know the ______ and ______. (B6.4)
a.
b.
c.
d.
e.
I, III, II
II, I, V
V, III, IV
IV, I, II
V, III, I
27. What is the simplest formula for a
compound composed of only carbon
and hydrogen and containing 14.3%
H? (B6.8)
a.
b.
c.
d.
e.
CH
CH4
C4 H
CH2
CH3
28. What is the molar mass of Al(NO3)3?
(B6.9)
a. 165.00
b. 56.99
c. 213.00
d. 88.99
e. 184.99
29. A substance has an empirical
formula of CH2. Its molar mass is
determined in a separate experiment
as 83.5. What is the most probable
molecular formula for this
compound? (B6.14)
a.
b.
c.
d.
e.
C2H4
C6H2
C4H2
CH12
C6H12
30. What is the percentage of potassium
in K3PO4? (B6.17)
a.
b.
c.
d.
e.
14.6%
29.2%
18.4%
55.2%
39.1%
Princeton 2012/Barron 4th ed.
31. Which of the following is NOT a
base metric unit (SI unit)? (B6.19)
a.
b.
c.
d.
e.
Meter
Liter
Mole
Second
Kilogram
32. Determine the empirical formula for
a compound that is 25% hydrogen
and 75% carbon. (B6.24)
a.
b.
c.
d.
e.
CH
CH2
CH4
C2H8
C4 H
Princeton 2012/Barron 4th ed.
Answer Key Unit 5 – Compounds and Moles
Multiple Choice
1. C
2. A
3. D
4. E
5. A
6. D
7. A
8. A
9. C
10. B
11. D
12. E
13. C
14. C
15. C
16. E
17. D
18. E
19. E
20. D
21. D
22. B
23. E
24. D
25. D
26. C
27. D
28. C
29. E
30. D
31. B
32. C