Calculations with moles

Get your GCSE Chemistry students confidently working with moles using this comprehensive resource pack that includes step-by-step explanations and practice questions (and answers).

What's included

• Step-by-step explanations of mole calculations suitable for Higher tier GCSE Chemistry and Combined Science
• Guided walk-through examples showing how to calculate the amount of substance and limiting reactants
• Practice questions with full answers for independent learning or peer assessment

Available as a free PDF download, or access the editable version with a science subscription.

How to use this resource

Suitable for Higher tier GCSE Chemistry and Combined Science, this resource provides a clear recap of mole calculations. Students follow a structured walk-through on calculating the amount of substance and limiting reactants, building confidence through guided examples. The included practice questions and answers allow for independent work and self-assessment, making it ideal for both classroom teaching and revision.

How to calculate moles in GCSE chemistry

This worksheet will help you practise two key areas in the Quantitative Chemistry topic, both requiring you to calculate number of moles:

• amount of substance in equations
• limiting reactants.

It is important that you know how to calculate the number of moles:
Can you rearrange this formula to calculate mass (g) and Mr?

Amount of substance in equations

Here, you are required to calculate the masses of reactants and products from balanced symbol equations.

Example question

Calcium chloride can be made as follows:

What mass (in grams) of CaCl2 could be made from 100 g of calcium?

(The equation has been balanced, but you may have to do this in an exam.)

Step 1

How many moles are there in 100 g of calcium?

Step 2

The balanced equation tells us there is a 1 : 1 ratio of Ca : CaCl2 in the reaction, so 2.5 moles of calcium will produce 2.5 moles of CaCl2

Step 3

What is the mass in grams of 2.5 moles of CaCl2?

Rearranging the first equation gives us:

Mass (g) = number of moles × Mr

The Mr of CaCl2 is 111, so the mass in grams of 2.5 moles of CaCl2 is:

Mass (g) = 2.5 × 111

Mass (g) = 277.5 g

Looking for more mole calculation practice?

Develop your students' understanding further with these related resources:

• Basic mole calculations
• Further moles practice questions
• Relative formula mass and moles
• Avogadro's constant
• Chemical moles trail activity
• Moles and yield calculations

Browse our full collection of GCSE chemistry moles resources.