Worksheet: Moles

In this worksheet, we will practice defining the mole in terms of Avogadro's constant and converting the mass of a substance to a number of moles.

Q1:

What is the mass of 0.443 mol of hydrazine, NH24?

Q2:

Sulfuric acid has a relative formula mass of 98 g/mol. What is the mass of 2.5 mol of sulfuric acid, to 3 significant figures?

Q3:

Ammonia has a relative formula mass of 17. How many moles of ammonia molecules are there in 34 g of ammonia?

Q4:

A 24 g sample of lithium hydride contains 3.0 moles of LiH units. What is the relative formula mass of lithium hydride?

Q5:

The mass of a substance (𝑚), its relative formula mass (𝑀), and the number of moles present (𝑛) can be related by a single formula. What is that formula?

  • A 𝑀 = 𝑚 𝑛
  • B 𝑛 = 𝑚 𝑀
  • C 𝑚 = 𝑀
  • D 𝑚 = 𝑛 𝑀
  • E 𝑛 = 𝑚 + 𝑀

Q6:

The complete combustion of acetylene (CH)22 produced 13.0 kg of water.

Calculate the number of moles of acetylene reacted.

Calculate the mass of oxygen reacted.

Q7:

Oxygen and mercury were produced by thermally decomposing 3.95 g of mercury(II) oxide.

Calculate the number of moles of mercury(II) oxide reacted.

Calculate the mass of oxygen gas produced.

Q8:

How many moles of atoms are there in 12 g of carbon-12?

Q9:

How is the atomic mass unit (u) defined?

  • A1 u is equal to the mass of a neutron.
  • B1 u is equal to 112th of the mass of a carbon-12 atom.
  • C1 u is equal to the mass of a proton.
  • D1 u is equal to the mass of a carbon-12 atom.
  • E1 u is equal to the mass of a hydrogen-1 atom.

Q10:

1,2-Dibromoethane (CHBr242) was produced by reacting 12.85 g of ethane with an excess of bromine.

Calculate the number of moles of 1,2-dibromoethane produced, to 3 significant figures.

Calculate the mass of bromine reacted.

Q11:

Calcium hydroxide and ammonium sulfate react to form ammonia, calcium sulfate, and water as the only products. Calculate, to 2 significant figures, the number of molecules of ammonia produced if 529 g of ammonium sulfate reacts with 385 g of calcium hydroxide.

  • A 7 . 2 × 1 0
  • B 6 . 3 × 1 0
  • C 8 . 1 × 1 0
  • D 4 . 8 × 1 0
  • E 9 . 3 × 1 0

Q12:

A prospector panning for gold in a river collects 15.81 g of pure gold. Calculate, to 3 significant figures, the number of Au atoms in this quantity of gold.

  • A 4 . 4 1 × 1 0 atoms
  • B 7 . 5 0 × 1 0 atoms
  • C 6 . 7 0 × 1 0 atoms
  • D 3 . 6 3 × 1 0 atoms
  • E 4 . 8 3 × 1 0 atoms

Q13:

To 3 significant figures, how many atomic mass units (u) are there in one gram (g) of a substance?

  • A 6 . 0 2 × 1 0
  • B 7 . 2 4 × 1 0
  • C 6 . 2 4 × 1 0
  • D 6 . 6 3 × 1 0
  • E 1 . 5 1 × 1 0

Q14:

Diamond is one form of elemental carbon. An engagement ring contains a diamond weighing 1.5 carats (1 carat = 200 mg). How many atoms are present in the diamond?

  • A 1 . 5 × 1 0
  • B 7 . 5 × 1 0
  • C 2 . 6 × 1 0
  • D 1 . 0 × 1 0
  • E 1 . 5 × 1 0

Q15:

Vitamin C is a covalent compound with the molecular formula CHO686. The recommended daily dietary allowance of vitamin C for children aged 4–8 years is 1.42×10 mol. What is the mass of this allowance in grams?

Q16:

The approximate daily dietary requirement of the amino acid leucine, CHNO6132, is 15 mg/kg of body weight. For a 65 kg person, what is this requirement in millimoles?

Q17:

A sample of magnesium required 5.00 g of hydrogen chloride gas to completely react.

Calculate the number of moles of magnesium reacted.

Calculate the mass of magnesium chloride produced.

Q18:

A 65 kg woman has 8.9×10 mol of hemoglobin (molar mass = 64,456 g/mol) in her blood.

How many hemoglobin molecules are there?

  • A 5 . 4 × 1 0
  • B 5 . 4 × 1 0
  • C 5 . 4 × 1 0
  • D 5 . 4 × 1 0
  • E 5 . 4 × 1 0

What is this quantity in grams?

Q19:

Gallium chloride is formed from excess gallium using 2.60 L of 1.44 M hydrochloric acid.

Calculate the number of moles of gallium reacted.

Calculate the mass of gallium chloride formed.

Q20:

A sample of ethene reacted with water to produce 9.55 g of ethanol.

Calculate the number of moles of ethene reacted.

Calculate the mass of water reacted.

Q21:

To 3 significant figures, how many molecules of water are produced by the complete combustion of 33.08 g of propane?

  • A 2 . 4 1 × 1 0
  • B 1 . 3 6 × 1 0
  • C 1 . 1 1 × 1 0
  • D 1 . 8 1 × 1 0
  • E 1 . 6 1 × 1 0

Q22:

Thermal decomposition of a sample of magnesium carbonate produced 283 g of carbon dioxide.

Calculate the number of moles of magnesium oxide produced.

Calculate the mass of magnesium carbonate reacted.

Q23:

The complete combustion of butane produced 15.0 kg of carbon dioxide.

Calculate the number of moles of oxygen reacted.

Calculate the mass of butane reacted.

Q24:

Sodium chloride was produced by reacting 5.50 g of sodium metal with chlorine.

Calculate the number of moles of sodium chloride produced.

Calculate the mass of chlorine reacted.

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