The Mole & Molar Mass — Drills · Grade 11 Science

Chapter: Reactions, Moles & Composition

What these drills covers

By the end of The Mole & Molar Mass you should be able to:

6 questions, numeric, multiple choice and written answer, each with a worked explanation.

Vocabulary used: mole (mol), Avogadro's number, molar mass, atomic mass, representative particle.

Problem 1

Calculate the molar mass of oxygen gas, O₂. (O = 16.00 g/mol.)
Answer and explanation

32 g/mol

O₂ = 2 × 16.00 = 32.00 g/mol.

Problem 2

One mole of carbon atoms has a mass of 12.01 g. How many atoms does it contain?
  1. 12
  2. 6.022 × 10²³
  3. 100
  4. 1.008
Answer and explanation

6.022 × 10²³

One mole of anything contains Avogadro's number of particles, 6.022 × 10²³.

Problem 3

How many moles are in 44.01 g of carbon dioxide? (Molar mass CO₂ = 44.01 g/mol.)
Answer and explanation

1 mol

moles = 44.01 g ÷ 44.01 g/mol = 1.00 mol.

Problem 4

What is the mass of 0.500 mol of glucose? (Molar mass C₆H₁₂O₆ = 180.18 g/mol.)
Answer and explanation

90.09 g

mass = moles × molar mass = 0.500 mol × 180.18 g/mol = 90.09 g.

Problem 5

Explain why chemists count particles in moles instead of counting atoms and molecules one at a time.
Answer and explanation

Atoms and molecules are far too small and too numerous to count individually. The mole (6.022 × 10²³ particles) bundles them into a group whose mass is large enough to weigh on a balance, so chemists can 'count' particles simply by measuring mass.

Problem 6

Calculate the molar mass of ammonium nitrate, NH₄NO₃. (N = 14.01, H = 1.01, O = 16.00 g/mol.)
Answer and explanation

80.06 g/mol

2 N + 4 H + 3 O = 2(14.01) + 4(1.01) + 3(16.00) = 28.02 + 4.04 + 48.00 = 80.06 g/mol.

Browse all courses