Moles and masses (RAM 1 d.p.) | Chemistry | Quizalize & Oak National Academy

Starter quiz

Which of the following is the correct chemical formula for calcium carbonate?

CACO3

CaCo₃

CaCO

CaCO₃ ✓

CaC
Match each keyword to the correct definition.

chemical equation

⇔

describes a reaction, indicating the reactants and products ✓

chemical formula

⇔

shows the number of atoms of each element in a substance ✓

coefficient

⇔

number placed in front of a chemical formula to balance an equation ✓

subscript

⇔

written slightly below and to the side of another character ✓

state symbol

⇔

indicates the physical state of substances in a reaction ✓
Which chemical equation is correctly balanced?

Mg + Cl → MgCl

Mg + Cl₂ → MgCl

Mg + Cl₂ → MgCl₂ ✓

Mg + 2Cl → MgCl₂
Match each element to its correct relative atomic mass.

He

⇔

4.0 ✓

Be

⇔

9.0 ✓

sodium

⇔

23.0 ✓

sulfur

⇔

32.1 ✓

silicon

⇔

28.1 ✓

scandium

⇔

45.0 ✓
The relative formula mass of sodium sulfide, Na₂S is ______.

'78.1' ✓
The relative formula mass of Al(OH)₃ is ______.

'78' ✓

Exit quiz

Which equation best matches this description of a chemical reaction? "Four moles of aluminium atoms reacts with three moles of oxygen molecules to form two moles of aluminium oxide formula units."

2Al₂O₃ → 4Al + 3O₂

4Al → 2Al₂O₃ + 3O₂

3O₂ → 2Al₂O₃ + 4Al

4Al + 3O₂ → 2Al₂O₃ ✓
Which of the following shows a correct mathematical relationship between moles, mass (g), and a substance's relative formula mass (RFM)?

moles = mass (g) × relative formula mass

mass (g) = moles ÷ relative formula mass

mass (g) = moles × relative formula mass ✓

moles = mass (g) ÷ relative formula mass ✓
The standard unit for mass is ______.

'grams' ✓
Place these samples in order from lowest mass to highest mass.

1

⇔

1 mol hydrogen

2

⇔

1 mol sodium

3

⇔

1 mol HCl

4

⇔

1 mol sodium chloride

5

⇔

1 mol Na₂O

6

⇔

1 mol Cl₂
How does the number of particles in 10 g of nitric acid, HNO₃, compare to the number of particles in 10 g of nitrogen?

There are fewer nitric acid particles in 10 g ✓

There are the same number of particles of nitrogen and nitric acid in 10 g

There are more nitric acid particles in 10 g
Match the mass (g) to the correct number of particles (moles).

6.0 g carbon

⇔

0.5 mol ✓

31.0 g phosphorus

⇔

1.0 mol ✓

70.5 g MgS

⇔

1.25 mol ✓

38.9 g LiF

⇔

1.5 mol ✓

279.7 g Br₂

⇔

1.75 mol ✓

80.0 g oxygen

⇔

2.5 mol ✓

Worksheet

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Lesson Details

Key learning points

The number of particles (atoms, ions, molecules etc.) in one mole of a substance is always the same.
The mass of one mole of a substance is equal to the relative mass of the substance measured in grams.
Mathematical relationships are manipulated to process practical results, calculating the number of moles in a substance.

Common misconception

Pupils struggle to link a mole to number of particles.

Use real world examples of converting volumes / masses into number of particles so pupils become more comfortable converting between moles, number of particles particles and masses.

Keywords

Mole - 1 mole of a substance is 6.02 × 10²³ particles of it. The mass of a mole of a substance is its relative mass in grams.
Avogadro's constant - Avogadro's constant is the number of particles in one mole of a substance (6.02 × 10²³ mol⁻¹).
Relative formula mass - The relative formula mass (RFM or Mᵣ) of a substance is the sum of the relative atomic masses of all the atoms in its formula.