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Additional Problems
1. Calculate the number of moles in each of the following masses:
a. 0.039 g of palladium
b. 8200 g of iron
c. 0.0073 kg of tantalum
d. 0.006 55 g of antimony
e. 5.64 kg of barium
f. 3.37  106 g of molybdenum
2. Calculate the mass in grams of each of the following amounts:
a. 1.002 mol of chromium
b. 550 mol of aluminum
c. 4.08  108 mol of neon
d. 7 mol of titanium
e. 0.0086 mol of xenon
f. 3.29  104 mol of lithium
3. Calculate the number of atoms in each of the following amounts:
a. 17.0 mol of germanium
b. 0.6144 mol of copper
c. 3.02 mol of tin
d. 2.0  106 mol of carbon
e. 0.0019 mol of zirconium
f. 3.227  1010 mol of potassium
4. Calculate the number of moles in each of the following quantities:
a. 6.022  1024 atoms of cobalt
b. 1.06  1023 atoms of tungsten
c. 3.008  1019 atoms of silver
d. 950 000 000 atoms of plutonium
e. 4.61  1017 atoms of radon
f. 8 trillion atoms of cerium
5. Calculate the number of atoms in each of the following masses:
a. 0.0082 g of gold
b. 812 g of molybdenum
c. 2.00  102 mg of americium
d. 10.09 kg of neon
e. 0.705 mg of bismuth
f. 37 g of uranium
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Holt ChemFile: Problem-Solving Workbook 69 Mole Concept
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6. Calculate the mass of each of the following:

a. 8.22  1023 atoms of rubidium
b. 4.05 Avogadro’s numbers of manganese atoms
c. 9.96  1026 atoms of tellurium
d. 0.000 025 Avogadro’s numbers of rhodium atoms
e. 88 300 000 000 000 atoms of radium
f. 2.94  1017 atoms of hafnium
7. Calculate the number of moles in each of the following masses:
a. 45.0 g of acetic acid, CH3COOH
b. 7.04 g of lead(II) nitrate, Pb(NO3)2
c. 5000 kg of iron(III) oxide, Fe2O3
d. 12.0 mg of ethylamine, C2H5NH2
e. 0.003 22 g of stearic acid, C17H35COOH
f. 50.0 kg of ammonium sulfate, (NH4)2SO4
8. Calculate the mass of each of the following amounts:
a. 3.00 mol of selenium oxybromide, SeOBr2
b. 488 mol of calcium carbonate, CaCO3
c. 0.0091 mol of retinoic acid, C20H28O2
d. 6.00  108 mol of nicotine, C10H14N2
e. 2.50 mol of strontium nitrate, Sr(NO3)2
f. 3.50  106 mol of uranium hexafluoride, UF6
9. Calculate the number of molecules or formula units in each of the following
amounts:
a. 4.27 mol of tungsten(VI) oxide, WO3
b. 0.003 00 mol of strontium nitrate, Sr(NO3)2
c. 72.5 mol of toluene, C6H5CH3
d. 5.11  107 mol of -tocopherol (vitamin E), C29H50O2
e. 1500 mol of hydrazine, N2H4
f. 0.989 mol of nitrobenzene C6H5NO2
10. Calculate the number of molecules or formula units in each of the following
masses:
a. 285 g of iron(III) phosphate, FePO4
b. 0.0084 g of C5H5N
c. 85 mg of 2-methyl-1-propanol, (CH3)2CHCH2OH
d. 4.6  104 g of mercury(II) acetate, Hg(C2H3O2)2
e. 0.0067 g of lithium carbonate, Li2CO3

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Holt ChemFile: Problem-Solving Workbook 70 Mole Concept
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11. Calculate the mass of each of the following quantities:

a. 8.39  1023 molecules of fluorine, F2
b. 6.82  1024 formula units of beryllium sulfate, BeSO4
c. 7.004  1026 molecules of chloroform, CHCl3
d. 31 billion formula units of chromium(III) formate, Cr(CHO2)3
e. 6.3  1018 molecules of nitric acid, HNO3
f. 8.37  1025 molecules of freon 114, C2Cl2F4
12. Precious metals are commonly measured in troy ounces. A troy ounce is
equivalent to 31.1 g. How many moles are in a troy ounce of gold? How many
moles are in a troy ounce of platinum? of silver?
13. A chemist needs 22.0 g of phenol, C6H5OH, for an experiment. How many
moles of phenol is this?
14. A student needs 0.015 mol of iodine crystals, I2, for an experiment. What mass
of iodine crystals should the student obtain?
15. The weight of a diamond is given in carats. One carat is equivalent to 200. mg.
A pure diamond is made up entirely of carbon atoms. How many carbon
atoms make up a 1.00 carat diamond?
16. 8.00 g of calcium chloride, CaCl2, is dissolved in 1.000 kg of water.
a. How many moles of CaCl2 are in solution? How many moles of water are
present?
b. Assume that the ionic compound, CaCl2 , separates completely into Ca2
and Cl ions when it dissolves in water. How many moles of each ion are
present in the solution?
17. How many moles are in each of the following masses?
a. 453.6 g (1.000 pound) of sucrose (table sugar), C12H22O11
b. 1.000 pound of table salt, NaCl
18. When the ionic compound NH4Cl dissolves in water, it breaks into one ammo-
nium ion, NH  
4 , and one chloride ion, Cl . If you dissolved 10.7 g of NH4Cl in
water, how many moles of ions would be in solution?
19. What is the total amount in moles of atoms in a jar that contains 2.41  1024
atoms of chromium, 1.51  1023 atoms of nickel, and 3.01  1023 atoms of
copper?
20. The density of liquid water is 0.997 g/mL at 25°C.
a. Calculate the mass of 250.0 mL (about a cupful) of water.
b. How many moles of water are in 250.0 mL of water? Hint: Use the result of
(a).
c. Calculate the volume that would be occupied by 2.000 mol of water at 25°C.
d. What mass of water is 2.000 mol of water?

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21. An Avogadro’s number (1 mol) of sugar molecules has a mass of 342 g, but an
Avogadro’s number (1 mol) of water molecules has a mass of only 18 g.
Explain why there is such a difference between the mass of 1 mol of sugar
and the mass of 1 mol of water.
22. Calculate the mass of aluminum that would have the same number of atoms
as 6.35 g of cadmium.
23. A chemist weighs a steel cylinder of compressed oxygen, O2 , and finds that it
has a mass of 1027.8 g. After some of the oxygen is used in an experiment, the
cylinder has a mass of 1023.2 g. How many moles of oxygen gas are used in
the experiment?
24. Suppose that you could decompose 0.250 mol of Ag2S into its elements.
a. How many moles of silver would you have? How many moles of sulfur
would you have?
b. How many moles of Ag2S are there in 38.8 g of Ag2S? How many moles of
silver and sulfur would be produced from this amount of Ag2S?
c. Calculate the masses of silver and sulfur produced in (b).

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Holt ChemFile: Problem-Solving Workbook 72 Mole Concept
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c. 60.4 kg; 1.88  104 dm3 c. 3  104 mol Fe2O3
d. 0.94 g/cm3; 5.3  104 m3 d. 2.66  104 mol C2H5NH2
e. 2.5  103 kg; 2.7  106 cm3 e. 1.13  105 mol C17H35COOH
7. 2.8 g/cm3 f. 378 mol (NH4)2SO4
8. a. 0.72 m 8. a. 764 g SeOBr2
b. 2.5  103 atoms b. 4.88  104 g CaCO3
9. 1300 L/min c. 2.7 g C20H28O2
10. 1.3  106 cal/h d. 9.74  106 g C10H14N2
11. 5.44 g/ cm3 e. 529 g Sr(NO3)2
12. 2.24  104 cm3 f. 1.23  103 g UF6
13. 32 000 uses 9. a. 2.57  1024 formula units WO3
14. 2500 L b. 1.81  1021 formula units Sr(NO3)2
15. 9.5 L/min c. 4.37  1025 molecules C6H5CH3
d. 3.08  1017 molecules C29H50O2
MOLE CONCEPT e. 9.0  1026 molecules N2H4
1. a. 3.7  104 mol Pd f. 5.96  1023 molecules C6H5NO2
b. 150 mol Fe 10. a. 1.14  1024 formula units FePO4
c. 0.040 mol Ta b. 6.4  1019 molecules C5H5N
d. 5.38  105 mol Sb c. 6.9  1020 molecules
e. 41.1 mol Ba (CH3)2CHCH2OH
f. 3.51  108 mol Mo d. 8.7  1017 formula units
2. a. 52.10 g Cr Hg(C2H3O2)2
b. 1.5  104 g or 15 kg Al e. 5.5  1019 formula units Li2CO3
c. 8.23  107 g Ne 11. a. 52.9 g F2
d. 3  102 g or 0.3 kg Ti b. 1.19  103 g or 1.19 kg BeSO4
e. 1.1 g Xe c. 1.388  105 g or 138.8 kg CHCl3
f. 2.28  105 g or 228 kg Li d. 9.6  1012 g Cr(CHO2)3
3. a. 1.02  1025 atoms Ge e. 6.6  104 g HNO3
b. 3.700  1023 atoms Cu f. 2.38  104 g or 23.8 kg C2Cl2F4
c. 1.82  1024 atoms Sn 12. 0.158 mol Au
d. 1.2  1030 atoms C 0.159 mol Pt
e. 1.1  1021 atoms Zr 0.288 mol Ag
f. 1.943  1014 atoms K 13.0.234 mol C6H5OH
4. a. 10.00 mol Co 14. 3.8 g I2
b. 0.176 mol W 15. 1.00  1022 atoms C
c. 4.995  105 mol Ag 16. a. 0.0721 mol CaCl2
d. 1.6  1015 mol Pu 55.49 mol H2O
e. 7.66  107 mol Rn b. 0.0721 mol Ca2
f. 1  1011 mol Ce 0.144 mol Cl
5. a. 2.5  1019 atoms Au 17. a. 1.325 mol C12H22O11
b. 5.10  1024 atoms Mo b. 7.762 mol NaCl
c. 4.96  1020 atoms Am 18. 0.400 mol ions
d. 3.011  1026 atoms Ne 19. 4.75 mol atoms
e. 2.03  1018 atoms Bi 20. a. 249 g H2O
f. 9.4  1016 atoms U b. 13.8 mol H2O
6. a. 117 g Rb c. 36.1 mL H2O
b. 223 g Mn d. 36.0 g H2O
c. 2.11  105 g Te 21. The mass of a sugar molecule is much
d. 2.6  103 g Rh greater than the mass of a water mole-
e. 3.31  108 g Ra cule. Therefore, the mass of 1 mol of
f. 8.71  105 g Hf sugar molecules is much greater than
7. a. 0.749 mol CH3COOH the mass of 1 mol of water molecules.
b. 0.0213 mol Pb(NO3)2 22. 1.52 g Al

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Holt Chemistry 324 Answer Key
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23. 0.14 mol O2 d. 39.17% O
24. a. 0.500 mol Ag e. 79.95% Br in CaBr2
0.250 mol S f. 78.767% Sn in SnO2
b. 0.157 mol Ag2S 4. a. 1.47 g O
0.313 mol Ag b. 26.5 metric tons Al
0.157 mol S c. 262 g Ag
c. 33.8 g Ag d. 0.487 g Au
5.03 g S e. 312 g Se
f. 3.1  104 g Cl
PERCENTAGE COMPOSITION 5. a. 40.55% H2O
1. a. HNO3 b. 43.86% H2O
1.60% H c. 20.70% H2O
22.23% N d. 28.90% H2O
76.17% O 6. a. Ni(C2H3O2)24H2O
b. NH3 23.58% Ni
82.22% N b. Na2CrO44H2O
17.78% H 22.22% Cr
c. HgSO4 c. Ce(SO4)24H2O
67.616% Hg 34.65% Ce
10.81% S 7. 43.1 kg Hg
21.57% O 8. malachite: 5.75  102 kg Cu
d. SbF5 chalcopyrite: 3.46  102 kg Cu
56.173% Sb malachite has a greater Cu content
43.83% F 9. a. 25.59% V
2. a. 7.99% Li b. 39.71% Sn
92.01% Br c. 22.22% Cl
b. 94.33% C 10. 319.6 g anhydrous CuSO4
5.67% H 11. 1.57 g AgNO3
c. 35.00% N 12. 54.3 g Ag
5.05% H 8.08 g S
59.96% O 13. 23.1 g MgSO47H2O
d. 2.15% H 14. 3.27  102 g S
29.80% N
68.06% O EMPIRICAL FORMULAS
e. 87.059% Ag 1. a. BaCl2
12.94% S b. BiO3H3 or Bi(OH)3
f. 32.47% Fe c. AlN3O9 or Al(NO3)3
13.96% C d. ZnC4H6O4 or Zn(CH3COO)2
16.29% N e. NiN2S2H8O8 or Ni(NH4)2SO4
37.28% S f. C2HBr3O2 or CBr3COOH
g. LiC2H3O2 2. a. CuF2
10.52% Li b. Ba(CN)2
36.40% C c. MnSO4
4.59% H 3. a. NiI2
48.49% O b. MgN2O6 or Mg(NO3)2
h. Ni(CHO2)2 c. MgS2O3, magnesium thiosulfate
39.46% Ni d. K2SnO3, potassium stannate
16.15% C 4. a. As2S3
1.36% H b. Re2O7
43.03% O c. N2H4O3 or NH4NO3
3. a. 46.65% N d. Fe2Cr3O12 or Fe2(CrO4)3
b. 23.76% S e. C5H9N3
c. 89.491% Tl f. C6H5F2N or C6H3F2NH2

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Holt Chemistry 325 Answer Key