Mole Concept
Q. How many grams are in 0.5 moles of glucose (C6H12O6)? (2023)
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A.
90 g
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B.
180 g
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C.
45 g
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D.
60 g
Solution
Molar mass of C6H12O6 = 6*12 + 12*1 + 6*16 = 180 g/mol. Mass = 0.5 moles x 180 g/mol = 90 g.
Correct Answer: A — 90 g
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Q. How many grams are in 4 moles of potassium chloride (KCl)? (2022)
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A.
74 g
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B.
148 g
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C.
296 g
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D.
37 g
Solution
Molar mass of KCl = 39 + 35.5 = 74.5 g/mol. Mass = 4 moles x 74.5 g/mol = 298 g.
Correct Answer: C — 296 g
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Q. How many grams are in 4 moles of sulfuric acid (H2SO4)? (2023)
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A.
196 g
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B.
98 g
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C.
392 g
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D.
294 g
Solution
Molar mass of H2SO4 = 2*1 + 32 + 4*16 = 98 g/mol. Mass = 4 moles x 98 g/mol = 392 g.
Correct Answer: C — 392 g
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Q. How many molecules are in 0.1 moles of oxygen gas (O2)? (2021)
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A.
6.022 x 10^22
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B.
6.022 x 10^23
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C.
1.2044 x 10^23
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D.
3.011 x 10^23
Solution
Number of molecules = moles x Avogadro's number = 0.1 moles x 6.022 x 10^23 molecules/mole = 6.022 x 10^22 molecules.
Correct Answer: A — 6.022 x 10^22
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Q. How many molecules are in 0.25 moles of oxygen gas (O2)? (2022)
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A.
3.011 x 10^23
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B.
6.022 x 10^22
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C.
1.2044 x 10^23
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D.
1.5055 x 10^23
Solution
Number of molecules = moles x Avogadro's number = 0.25 moles x 6.022 x 10^23 molecules/mole = 1.5055 x 10^23 molecules.
Correct Answer: B — 6.022 x 10^22
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Q. How many molecules are present in 2 moles of water (H2O)? (2022) 2022
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A.
6.022 x 10^23
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B.
1.2044 x 10^24
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C.
3.011 x 10^23
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D.
1.2044 x 10^23
Solution
Number of molecules = moles x Avogadro's number = 2 moles x 6.022 x 10^23 molecules/mole = 1.2044 x 10^24 molecules.
Correct Answer: B — 1.2044 x 10^24
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Q. How many moles are in 100 grams of NaOH? (2022)
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A.
2.5
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B.
1.25
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C.
0.5
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D.
3
Solution
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol. Number of moles = mass/molar mass = 100 g / 40 g/mol = 2.5 moles.
Correct Answer: B — 1.25
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Q. How many moles are in 32 grams of O2? (2021)
Solution
Molar mass of O2 = 16*2 = 32 g/mol. Number of moles = mass/molar mass = 32g/32g/mol = 1 mole.
Correct Answer: A — 1
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Q. If 0.5 moles of a gas occupy 12.2 liters at STP, what is the molar volume of the gas? (2023)
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A.
22.4 L
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B.
24 L
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C.
12.2 L
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D.
6.1 L
Solution
At STP, 1 mole of gas occupies 22.4 liters. Therefore, the molar volume is 22.4 L.
Correct Answer: A — 22.4 L
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Q. If you have 0.25 moles of sulfuric acid (H2SO4), what is its mass? (2023)
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A.
49 g
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B.
98 g
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C.
25 g
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D.
12.5 g
Solution
Molar mass of H2SO4 = 2*1 + 32 + 4*16 = 98 g/mol. Mass = 0.25 moles x 98 g/mol = 24.5 g.
Correct Answer: B — 98 g
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Q. What is the mass of 3 moles of NaCl? (2020) 2020
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A.
87 g
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B.
58.5 g
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C.
174 g
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D.
3 g
Solution
Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol. Mass = moles x molar mass = 3 moles x 58.5 g/mol = 174 g.
Correct Answer: C — 174 g
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Q. What is the mass of 3 moles of sodium chloride (NaCl)? (2023)
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A.
58.5 g
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B.
117 g
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C.
175.5 g
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D.
29.25 g
Solution
The molar mass of NaCl is 58.5 g/mol. Therefore, 3 moles of NaCl weigh 3 x 58.5 g = 175.5 g.
Correct Answer: B — 117 g
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Q. What is the number of moles in 10 grams of H2? (2020)
Solution
Molar mass of H2 = 2 g/mol. Number of moles = mass/molar mass = 10 g / 2 g/mol = 5 moles.
Correct Answer: A — 0.5
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Q. What is the number of moles in 10 grams of hydrogen gas (H2)? (2019)
Solution
Molar mass of H2 = 2 g/mol. Number of moles = 10g/2g/mol = 5 moles.
Correct Answer: B — 0.5
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Q. What is the number of moles in 250 mL of a 2 M NaCl solution? (2021)
Solution
Moles = Molarity x Volume (L) = 2 M x 0.250 L = 0.5 moles.
Correct Answer: A — 0.5
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Q. What is the number of moles in 44 grams of carbon dioxide (CO2)? (2023)
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A.
1 mole
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B.
2 moles
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C.
0.5 moles
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D.
0.25 moles
Solution
The molar mass of CO2 is 44 g/mol. Therefore, 44 g of CO2 corresponds to 1 mole.
Correct Answer: A — 1 mole
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Q. What is the number of moles in 44 grams of CO2? (2021) 2021
Solution
Molar mass of CO2 = 12 + 16*2 = 44 g/mol. Number of moles = mass/molar mass = 44g/44g/mol = 1 mole.
Correct Answer: A — 1
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Q. What is the number of moles in 500 mL of a 2 M NaCl solution? (2023)
Solution
Moles = Molarity x Volume (L) = 2 moles/L x 0.5 L = 1 mole.
Correct Answer: A — 1
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Q. What is the volume of 1 mole of an ideal gas at STP? (2019) 2019
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A.
22.4 L
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B.
24 L
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C.
1 L
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D.
10 L
Solution
At STP, 1 mole of an ideal gas occupies 22.4 liters.
Correct Answer: A — 22.4 L
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