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Worksheet: Moles

Q1:

The complete combustion of acetylene ( C H ) 2 2 produced 13.0 kg of water.

Calculate the number of moles of acetylene reacted.

Calculate the mass of oxygen reacted.

Q2:

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.

Q3:

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

Q4:

How is the atomic mass unit (u) defined?

  • A 1 u is equal to the mass of a neutron.
  • B 1 u is equal to the mass of a proton.
  • C 1 u is equal to the mass of a carbon-12 atom.
  • D 1 u is equal to 1 1 2 th of the mass of a carbon-12 atom.
  • E 1 u is equal to the mass of a hydrogen-1 atom.

Q5:

1,2-Dibromoethane ( C H B r 2 4 2 ) 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.

Q6:

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

Q7:

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

  • A 4 . 4 1 × 1 0 2 3 atoms
  • B 7 . 5 0 × 1 0 2 4 atoms
  • C 6 . 7 0 × 1 0 2 2 atoms
  • D 4 . 8 3 × 1 0 2 2 atoms
  • E 3 . 6 3 × 1 0 2 3 atoms

Q8:

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

  • A 6 . 2 4 × 1 0 1 8
  • B 7 . 2 4 × 1 0 2 2
  • C 1 . 5 1 × 1 0 3 3
  • D 6 . 0 2 × 1 0 2 3
  • E 6 . 6 3 × 1 0 3 4

Q9:

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

Q10:

Vitamin C is a covalent compound with the molecular formula C H O 6 8 6 . The recommended daily dietary allowance of vitamin C for children aged 4–8 years is 1 . 4 2 × 1 0 4 mol. What is the mass of this allowance in grams?

Q11:

The approximate daily dietary requirement of the amino acid leucine, C H N O 6 1 3 2 , is 15 mg/kg of body weight. For a 65 kg person, what is this requirement in moles?

Q12:

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.

Q13:

A 65-kg woman has 8 . 9 × 1 0 3 mol of hemoglobin (molar mass = 6 4 4 5 6 g/mol) in her blood.

How many hemoglobin molecules is this?

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

What is this quantity in grams?

Q14:

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.

Q15:

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.

Q16:

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

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

Q17:

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.

Q18:

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.

Q19:

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.