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1. Write out conversion factors between the moles of each element and the
moles of the compound C5H12
Answer:
1 mole of 𝐶5 𝐻12 consist 5 moles of 𝐶 atom and 12 moles of 𝐻 atom.
Conversion factor for Carbon and Hydrogen element are as follows:
5 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶
Number of Carbon atom (C) =
× 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶5 𝐻12
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝐶5 𝐻12
12 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐻
Number of Hydrogen atom (H) =
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝐶5 𝐻12
×
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶5 𝐻12
2. Write out conversion factors between the moles of each element and the
moles of the compound C27H46O
Answer:
1 mole of 𝐶27 𝐻46 𝑂 consist 27 moles of 𝐶 atom, 46 moles of 𝐻 atom and 1
mole of O atom.
Conversion factor for Carbon, Hydrogen and Oxygen element are as follows:
27 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶
Number of Carbon atom (C) =
×
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝐶27 𝐻46 𝑂
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶27 𝐻46 𝑂
Number of Hydrogen atom (H) =
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶27 𝐻46 𝑂
Number of Oxygen atom (O) =
46 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐻
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝐶27 𝐻46 𝑂
1 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑂
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝐶27 𝐻46 𝑂
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶27 𝐻46 𝑂
×
×
3. Write out conversion factors between the moles of each element and the
moles of the compound C6H12O6
Answer:
1 mole of 𝐶6 𝐻12 𝑂6 consist 6 moles of 𝐶 atom, 12 moles of 𝐻 atom and 6 mole
of O atom.
Conversion factor for Carbon, Hydrogen and Oxygen element are as follows:
6 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶
Number of Carbon atom (C) =
×
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝐶27 𝐻46 𝑂
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶6 𝐻12 𝑂6
Number of Hydrogen atom (H) =
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶6 𝐻12 𝑂6
Number of Oxygen atom (O) =
12 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐻
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝐶27 𝐻46 𝑂
6 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑂
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝐶27 𝐻46 𝑂
×
×
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶6 𝐻12 𝑂6
4. Write out the conversion factor of the given element in the given compound
using the mass percent composition
a) Carbon dioxide is 27.19% carbon by mass
Answer:
Molar mass of 𝐶𝑂2 = 44 g/mol
27.19
44 g of 𝐶𝑂2 contain =
× 44 ≈ 11.96 g of carbon
Conversion factor =
100
11.96𝑔 𝐶
44𝑔 𝐶𝑂2
b) Butane is 17.34% hydrogen by mass
Answer:
Molar mass of Butane = 58.12 g/mol
17.34
58.12 g of butane contain = 58.12 ×
≈ 10.08 g H
Conversion factor =
10.08𝑔 𝐻
58.12𝑔 𝐵𝑢𝑡𝑎𝑛𝑒
100
c) C6H8O7 is 58.29% oxygen by mass
Answer:
Molar mass of 𝐶6 𝐻8 𝑂7 = 192.12 g/mol
58.29
192.12 g of 𝐶6 𝐻8 𝑂7 = 192.12 ×
≈ 111.98 g O
Conversion factor =
100
111.98𝑔 𝑂
192.12𝑔 𝐶6 𝐻8 𝑂7
5. Write out the conversion factor of the given element in the given compound
using the mass percent composition
a) Ethanol is 13.13% hydrogen by mass
Answer:
Molar mass of 𝐸𝑡ℎ𝑎𝑛𝑜𝑙 𝐶2 𝐻5 𝑂𝐻 = 46.07 g/mol
13.13
46.07 g of 𝐶2 𝐻5 𝑂𝐻 = 46.07 ×
≈ 6.05 g H
Conversion factor =
6.05𝑔 𝐻
100
46.07𝑔 𝐶2 𝐻5 𝑂𝐻
b) Aluminum nitrate is 19.73% nitrogen by mass
Answer:
Molar mass of 𝐴𝑙𝑢𝑚𝑖𝑛𝑢𝑚 𝑁𝑖𝑡𝑟𝑎𝑡𝑒 = 212.996 g/mol
19.73
212.996 g of 𝐴𝑙𝑢𝑚𝑖𝑛𝑢𝑚 𝑁𝑖𝑡𝑟𝑎𝑡𝑒 = 212.996 ×
≈ 42.02 g N
Conversion factor =
100
42.02𝑔 𝑁
46.07𝑔 𝐴𝑙𝑢𝑚𝑖𝑛𝑢𝑚 𝑁𝑖𝑡𝑟𝑎𝑡𝑒
c) Methyl butanoate is 58.8% carbon by mass
Answer:
Molar mass of 𝑀𝑒𝑡ℎ𝑦𝑙 𝑏𝑢𝑡𝑎𝑛𝑜𝑎𝑡𝑒 = 102.13 g/mol
58.8
102.13 g of 𝑀𝑒𝑡ℎ𝑦𝑙 𝑏𝑢𝑡𝑎𝑛𝑜𝑎𝑡𝑒 = 102.13 ×
≈ 60.05 g C
Conversion factor =
60.05𝑔 𝐶
102.13𝑔 𝑀𝑒𝑡ℎ𝑦𝑙 𝑏𝑢𝑡𝑎𝑛𝑜𝑎𝑡𝑒
100
6. Write out the conversion factor of the given element in the given compound
using the mass percent composition
a) Propane is 81.68% carbon by mass
Answer:
Molar mass of 𝑃𝑟𝑜𝑝𝑎𝑛𝑒 = 44.1 g/mol
81.68
44.1 g of 𝑃𝑟𝑜𝑝𝑎𝑛𝑒 = 44.1 ×
≈ 36.02 g C
Conversion factor =
100
36.02𝑔 𝐶
44.1𝑔 𝑃𝑟𝑜𝑝𝑎𝑛𝑒
b) Ethylene is 14.14% hydrogen by mass
Answer:
Molar mass of 𝐸𝑡ℎ𝑦𝑙𝑒𝑛𝑒 = 28.05 g/mol
14.14
28.05g of 𝐸𝑡ℎ𝑦𝑙𝑒𝑛𝑒 = 28.05 ×
≈ 3.96 g H
Conversion factor =
3.96𝑔 𝐻
100
28.05𝑔 𝐸𝑡ℎ𝑦𝑙𝑒𝑛𝑒
c) Aluminum oxide is 52.9% aluminum by mass
Answer:
Molar mass of 𝐴𝑙𝑢𝑚𝑖𝑛𝑢𝑚 𝑂𝑥𝑖𝑑𝑒 = 101.96 g/mol
52.9
101.96g of 𝐴𝑙𝑢𝑚𝑖𝑛𝑢𝑚 𝑂𝑥𝑖𝑑𝑒 = 101.96 ×
≈ 53.94 g Al
Conversion factor =
53.94𝑔 𝐴𝑙
101.96𝑔 𝐴𝑙𝑢𝑚𝑖𝑛𝑢𝑚 𝑂𝑥𝑖𝑑𝑒
100
Answers:
1 mole = 6.02𝑥 1023 𝑎𝑡𝑜𝑚𝑠
8.22 𝑥 1024 𝐴𝑠 𝑎𝑡𝑜𝑚𝑠
a)
b)
c)
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
6.77 𝑥 1023 𝐿𝑖 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
2.10 𝑥 1021 𝑆 𝑎𝑡𝑜𝑚𝑠
d)
≈ 13.65 As atoms
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
4.41 𝑥 1022 𝑁𝑒 𝑎𝑡𝑜𝑚𝑠
≈ 0.07 Ne atoms
≈ 1.12 Li atoms
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
≈ 3.48 x 10³ S atoms
Answers:
1 mole = 6.02𝑥 1023 𝑎𝑡𝑜𝑚𝑠
a) 0.994 𝑚𝑜𝑙 𝐹 𝑥 6.02 𝑥 1023
𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙𝑒
23 𝑎𝑡𝑜𝑚𝑠
b) 4.39 𝑚𝑜𝑙 𝑆𝑟 𝑥 6.02 𝑥 10
c) 9.1 𝑥 10−3 𝑚𝑜𝑙 𝐵 𝑥
≈ 5.98 𝑥 1023 𝐹 𝑎𝑡𝑜𝑚𝑠
≈ 2.642 𝑥 1024 𝑆𝑟 𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙𝑒
𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023
𝑚𝑜𝑙𝑒
23 𝑎𝑡𝑜𝑚𝑠
d) 13.8 𝑚𝑜𝑙 𝐶𝑙 𝑥 6.02 𝑥 10
𝑚𝑜𝑙𝑒
≈ 5.478 𝑥 1021 𝐵 𝑎𝑡𝑜𝑚𝑠
≈ 8.307 𝑥 1024 𝐶𝑙 𝑎𝑡𝑜𝑚𝑠
Answers:
1 mole = 6.02𝑥 1023 𝑎𝑡𝑜𝑚𝑠
a)
b)
c)
d)
2.13 𝑥 1025 𝐻𝑒 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
3.65 𝑥 1022 𝐺𝑎 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
6.022 𝑥 1023 𝑀𝑔 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
1.04 𝑥 1024 𝐶𝑢 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
≈ 35.38 He atoms
≈ 0.06 Ga atoms
≈ 1 Mg atoms
≈ 1.7 Cu atoms
Answers:
1 mole = 6.02𝑥 1023 𝑎𝑡𝑜𝑚𝑠
𝑎) 0.0112 𝑚𝑜𝑙 𝑆𝑒 𝑥 6.02 𝑥 1023
b)
1.55 𝑥 1023 𝐾 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
7.12 𝑥 1022 𝐵𝑟 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
𝑚𝑜𝑙𝑒
≈ 6.74 𝑥 1021 𝑆𝑒 𝑎𝑡𝑜𝑚𝑠
≈ 0.25 K atoms
𝑐) 2.34 𝑚𝑜𝑙 𝑇𝑖 𝑥 6.02 𝑥 1023
d)
𝑎𝑡𝑜𝑚𝑠
𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙𝑒
≈ 1.408 𝑥 1024 𝑇𝑖 𝑎𝑡𝑜𝑚𝑠
≈ 0.118 Br atoms
Answers:
𝑎) 13.2 𝑚𝑜𝑙 𝑃 𝑥 6.02 𝑥 1023
𝑏) 0.222 𝑚𝑜𝑙 𝐴𝑢 𝑥 6.02 𝑥
c)
d)
5.02 𝑥 1024 𝐹 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
1.98 𝑥 1023 𝐵𝑒 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
𝑎𝑡𝑜𝑚𝑠
≈ 7.946 𝑥 1024 𝑃 𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙𝑒
23 𝑎𝑡𝑜𝑚𝑠
10
𝑚𝑜𝑙𝑒
≈ 1.336 𝑥 1023 𝐴𝑢 𝑎𝑡𝑜𝑚𝑠
≈8.34 F atoms
≈ 0.328 Be atoms
Answers:
a)
9.54 𝑥 1021 𝑂 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
−6
𝑏) 1.30 𝑥 10
≈ 0.01584 O atoms
𝑚𝑜𝑙 𝑍𝑟 𝑥 6.02 𝑥 1023
𝑐) 25.3 𝑚𝑜𝑙 𝐵𝑘 𝑥 6.02 𝑥 1023
d)
7.71 𝑥 1024 𝐵𝑎 𝑎𝑡𝑜𝑚𝑠
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙
𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙𝑒
𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙𝑒
≈ 7.826 𝑥 1017 𝑍𝑟 𝑎𝑡𝑜𝑚𝑠
≈ 1.523 𝑥 1025 𝐴𝑢 𝑎𝑡𝑜𝑚𝑠
≈ 12.807 Ba atoms
Answers:
a)
b)
75.4 𝑔 𝑁
14
𝑔
𝑚𝑜𝑙 𝑁
≈ 5.3857 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑁
13.9 𝑔 𝑁
183.84
𝑔
𝑚𝑜𝑙 𝑁
≈ 0.0756 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑊
c) 0.00784 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐺𝑒 × 72.64
d) 4.09 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑅𝑏 × 85.46
𝑔
𝑔
𝑚𝑜𝑙
𝑚𝑜𝑙
≈ 0.5694 g of Ge
≈ 349.53 g of Rb
Answers:
62.4 𝑔 𝐶𝑜
a)
≈ 1.0588 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶𝑜
𝑔
58.93
𝑚𝑜𝑙 𝐶𝑜
b) 2.23 × 10−4 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐻𝑔 × 200.59
c) 18.6 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑇𝑒 × 127.6
d)
4.97 𝑔 𝐴𝑙
26.98
𝑔
𝑚𝑜𝑙 𝐴𝑙
𝑔
𝑚𝑜𝑙
𝑔
𝑚𝑜𝑙
≈ 0.447 g of Hg
≈ 2,373.36 g of Te
≈ 0.1842 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐴𝑙
Answers:
a) 244 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐿𝑖 × 6.941
𝑔
𝑚𝑜𝑙
𝑔
b) 0.653 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑌 × 88.90
c)
d)
20.7 𝑔 𝐵
𝑚𝑜𝑙
≈ 58.05 g of Y
≈ 1.9147 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐵
𝑔
10.811
𝑚𝑜𝑙 𝐵
0.00422 𝑔 𝐻𝑒
4.002
≈ 1,693.604 g of Li
𝑔
𝑚𝑜𝑙 𝐻𝑒
≈ 0.001 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐻𝑒
Mass of atoms = moles of atoms × Molar mass (g/mol) of element.
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑎𝑡𝑜𝑚𝑠
⇒ Mass of atoms =
× 𝑀𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑒𝑙𝑒𝑚𝑒𝑛𝑡.
′
𝐴𝑣𝑜𝑔𝑎𝑑𝑟𝑜 𝑠 𝑁𝑢𝑚𝑏𝑒𝑟
Answers:
a)
b)
c)
d)
4.45 𝑥 1019
6.02 𝑥 1023
5.50×1024
6.022×1023
2.08×1021
6.022×1023
7.31×1024
6.022×1023
× 107.87 ≈ 0.008 𝑔 𝑜𝑓 𝐴𝑔
× 208.98 ≈ 1908.652 g of Bi
× 78.96 ≈ 0.273 g of Se
× 39.95 ≈ 484.946 g of Ar
Answers:
Number of atoms = moles of element × Avogadro’s number
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑒𝑙𝑒𝑚𝑒𝑛𝑡
Moles of element =
𝑀𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑒𝑙𝑒𝑚𝑒𝑛𝑡
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑒𝑙𝑒𝑚𝑒𝑛𝑡
⇒ Number of atoms =
a)
b)
c)
d)
14.8
26.98
3.98
40.08
1.90
58.93
26.7
32.07
𝑀𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑒𝑙𝑒𝑚𝑒𝑛𝑡
× 6.022 × 1023
× 6.022 × 1023 ≈ 3.303 × 1023 atoms of Al
× 6.022 × 1023 ≈ 4.067 × 1022 atoms of Ca
× 6.022 × 1023 ≈ 1.942 × 1022 atoms of Co
× 6.022 × 1023 ≈ 5.014 × 1023 atoms of S
Answers:
Mass = moles of element x mass of Element
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑎𝑡𝑜𝑚𝑠
Moles of element =
′
⇒ Mass =
𝐴𝑣𝑜𝑔𝑟𝑎𝑑𝑜 𝑠𝑛𝑢𝑚𝑏𝑒𝑟
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑎𝑡𝑜𝑚𝑠
𝐴𝑣𝑜𝑔𝑟𝑎𝑑𝑜′ 𝑠𝑛𝑢𝑚𝑏𝑒𝑟
3.72 ×1020
a) Mass of Cd =
b) Mass of Sb =
c) Mass of F =
6.02 ×1023
6.01 ×1023
6.02 ×1023
9.43 ×1026
× 112.41 𝑔 ≈ 0.069 𝑔 𝑜𝑓 𝐶𝑑
× 121.76 𝑔 ≈ 121.55 𝑔 𝑜𝑓 𝑆𝑏
× 19 𝑔 ≈ 29,762.46 𝑔 𝑜𝑓 𝐹
6.02 ×1023
3.72 ×1020
d) Mass of Re =
× 𝑚𝑎𝑠𝑠 𝑜𝑓 𝐸𝑙𝑒𝑚𝑒𝑛𝑡
6.02 ×1023
× 186.20 𝑔 ≈ 115.06 𝑔 𝑜𝑓 𝑅𝑒
Answers:
a) Mass of Sn = 118.71
Atoms of Sn = 6.02 ×
𝑔
× 3.65 𝑚𝑜𝑙𝑒𝑠 ≈ 2.1973 × 1024 𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙
𝑎𝑡𝑜𝑚𝑠
1023
𝑚𝑜𝑙
× 0.0983 𝑚𝑜𝑙𝑒𝑠 ≈ 5.917 × 1022 𝑎𝑡𝑜𝑚𝑠
b) Mass of Xe= 131.293
Atoms of Xe = 6.02 ×
c) Moles of H =
65.5 𝑚𝑔
1
𝑔
𝑚𝑜𝑙
× 0.0983 𝑚𝑜𝑙𝑒𝑠 ≈ 12.9 𝑔
≈ 0.0655 moles
Atoms of H = 6.02 × 1023
d) Moles of Si =
× 3.65 𝑚𝑜𝑙𝑒𝑠 ≈ 433.29 𝑔
𝑚𝑜𝑙
𝑎𝑡𝑜𝑚𝑠
1023
𝑚𝑜𝑙
𝑔
𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙
4.35 ×1024 𝑎𝑡𝑜𝑚𝑠
𝑎𝑡𝑜𝑚𝑠
6.02 ×1023
𝑚𝑜𝑙
𝑔
Mass of Si = 28.08
𝑚𝑜𝑙
× 0.0655 𝑚𝑜𝑙𝑒𝑠 ≈ 3.943 × 1022 𝑎𝑡𝑜𝑚𝑠
≈ 7.226 moles
× 7.226 𝑚𝑜𝑙𝑒𝑠 ≈ 202.90 𝑔
6.18 ×1021 𝑎𝑡𝑜𝑚𝑠
a) Moles of Ca =
𝑎𝑡𝑜𝑚𝑠
6.02 ×1023
𝑚𝑜𝑙
𝑔
Mass of Ca = 40.07
b) Moles of Br =
× 0.010 𝑚𝑜𝑙𝑒𝑠 ≈ 0.40007 𝑔
𝑚𝑜𝑙
0.138 𝑘𝑔
79.90
𝑔
𝑚𝑜𝑙
≈ 1.727 moles
Atoms of Br = 6.02 × 1023
c) Moles of Ga =
𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙
9.29 ×1023 𝑎𝑡𝑜𝑚𝑠
Mass of Ga = 69.7
𝑎𝑡𝑜𝑚𝑠
6.02 ×1023
𝑚𝑜𝑙
𝑔
𝑚𝑜𝑙
d) Mass of K = 39.10
Atoms of K = 6.02 ×
≈ 0.010 moles
× 1.727 𝑚𝑜𝑙𝑒𝑠 ≈ 1.039 × 1024 𝑎𝑡𝑜𝑚𝑠
≈ 1.543 moles
× 1.543 𝑚𝑜𝑙𝑒𝑠 ≈ 107.54 𝑔
𝑔
× 10.4 𝑚𝑜𝑙𝑒𝑠 ≈ 406.64 𝑔
𝑚𝑜𝑙
𝑎𝑡𝑜𝑚𝑠
1023
𝑚𝑜𝑙
× 10.4 𝑚𝑜𝑙𝑒𝑠 ≈ 6.26 × 1024 𝑎𝑡𝑜𝑚𝑠
a) Moles of Be =
226 𝑚𝑔
9
𝑔
𝑚𝑜𝑙
≈ 0.025 moles
Atoms of Be = 6.02 × 1023
b) Moles of S =
Mass of S = 32
× 0.025 𝑚𝑜𝑙𝑒𝑠 ≈ 1.505 × 1022 𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙
7.36 ×1020 𝑎𝑡𝑜𝑚𝑠
𝑎𝑡𝑜𝑚𝑠
6.02 ×1023
𝑚𝑜𝑙
𝑔
𝑚𝑜𝑙
≈ 1.22 × 10−3 moles
× 1.22 × 10−3 𝑚𝑜𝑙 ≈ 0.039 𝑔
c) Mass of Nb = 92.9
𝑔
𝑚𝑜𝑙
× 0.104 𝑚𝑜𝑙𝑒𝑠 ≈ 9.66 𝑔
Atoms of Nb = 6.02 × 1023
d) Moles of N =
𝑎𝑡𝑜𝑚𝑠
0.00391 𝑘𝑔
14
𝑔
𝑚𝑜𝑙
𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙
× 0.104 𝑚𝑜𝑙𝑒𝑠 ≈ 6.26 × 1022 𝑎𝑡𝑜𝑚𝑠
≈ 0.279 moles
Atoms of N = 6.02 × 1023
𝑎𝑡𝑜𝑚𝑠
𝑚𝑜𝑙
× 0.279 𝑚𝑜𝑙𝑒𝑠 ≈ 1.68 × 1023 𝑎𝑡𝑜𝑚𝑠
Mass of compound = Moles of compound × Molar mass of compound
Molar mass of carbon monoxide (𝐶𝑂) = 28.01 g/mol
Molar mass of sulphur hexafluoride (𝑆𝐹6 ) = 146.06 g/mol
Molar mass of potassium hydroxide (𝐾𝑂𝐻) = 56.1 g/mol
Molar mass of lithium nitrate (𝐿𝑖𝑁𝑂3 ) = 68.95 g/mol
a) Mass of carbon monoxide = 6.10 × 28.01 ≈ 170.9 g
b) Mass of sulphur hexafluoride = 0.364 × 146.06 ≈ 53.2 g
c) Mass of potassium hydroxide = 4.44 × 56.1 ≈ 249.1 g
d) Mass of lithium nitrate = 1.71 × 68.95 ≈ 117.9 g
Mass of compound = Moles of compound × Molar mass of compound
Molar mass of sodium chloride (𝑁𝑎𝐶𝑙) = 22.99 g/mol
Molar mass of Nitrogen dioxide (𝑁𝑂2 ) = 46 g/mol
Molar mass of boron tribromide (𝐵𝐵𝑟3 ) = 250.52 g/mol
Molar mass of xenon tetroxide (𝑋𝑒𝑂4 ) = 195.29 g/mol
a) Mass of sodium chloride = 13.4 𝑚𝑜𝑙 × 22.99
b) Mass of Nitrogen dioxide = 0.223 𝑘𝑚𝑜𝑙 × 46
𝑔
≈ 308.06 g
𝑚𝑜𝑙
𝑔
𝑚𝑜𝑙
≈ 10,256 g
c) Mass of boron tribromide = 0.00322 𝑚𝑜𝑙 × 250.52
d) Mass of xenon tetroxide = 144 𝑚𝑚𝑜𝑙 × 195.29
Moles of compound =
𝑔
𝑚𝑜𝑙
𝑔
𝑚𝑜𝑙
≈ 0.806 g
≈ 28.12 g
𝑀𝑎𝑠𝑠
𝑀𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑
Molar mass of ammonium iodide (𝑁𝐻4 𝐼) = 144.94 g/mol
Molar mass of potassium cyanide (𝐾𝐶𝑁) = 65.12 g/mol
Molar mass of sodium sulfate (𝑁𝑎2 𝑆𝑂4 ) = 142.04 g/mol
Molar mass of hydrocholoric acid (𝐻𝐶𝑙) = 36.46 g/mol
a) Moles of ammonium iodide =
b) Moles of potassium cyanide =
c) Moles of sodium sulfate=
29.8 𝑔
144.94 𝑔/𝑚𝑜𝑙
8.34 𝑔
65.12 𝑔/𝑚𝑜𝑙
3.5 𝑚𝑔
≈ 0.128 mol
≈ 2.46 𝑥 10...