Study Hub

Study Guides

This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.

Back to Study HubBrowse Year 10 Science Guides

Year 10 - Science

Mass in a chemical reaction: using moles (RAM 1 d.p.)

Calculations involving masses

Unit Summary

This unit covers writing chemical formulae, balancing equations, and using the conservation of mass. It includes calculating moles, empirical formulae, relative formula masses, and theoretical yields. Emphasis is on stoichiometry, concentration, gas volumes, and using standard form.

Lesson Summary

You will learn to interpret a balanced symbol equation to predict the mass of either a reactant or a product.

Key Notes

  • Stoichiometry means 'measuring elements', from the Greek 'stoikhein' – meaning element and 'metron' – to measure.
  • Chemical equations should be interpreted in terms of moles (i.e. 1 mole of this reacts with 2 moles of that).
  • The mass of each reactant that does react can be worked out from the relative formula masses in the chemical equation.
  • In a chemical reaction, the atoms in reactants are rearranged and are the same atoms that are in the products.
  • The mass of products in a chemical reaction is equal to the mass of the reactants.

Vocabulary To Learn

  • stoichiometry: Stoichiometry refers to the molar ratio of the reactants and products in a chemical reaction.
  • 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.
  • 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.

Common Mistakes To Avoid

  • Pupils struggle to recall the order of steps required to mathematically process the available information in order to answer the question.

3 Quick Questions (With Answers)

1. Explain the scientific idea in this lesson using two key points.

Stoichiometry means 'measuring elements', from the Greek 'stoikhein' – meaning element and 'metron' – to measure. Chemical equations should be interpreted in terms of moles (i.e. 1 mole of this reacts with 2 moles of that).

2. Define this scientific word and use it in context. 'stoichiometry'

Stoichiometry refers to the molar ratio of the reactants and products in a chemical reaction. Include the word in a full scientific explanation, not as a single label.

3. Correct this common scientific misunderstanding.

Mistake: Pupils struggle to recall the order of steps required to mathematically process the available information in order to answer the question. Correction: Colour-coding the steps can help pupils remember how many steps are involved. Much practice and perseverance is needed to create and maintain the memory pathway of the mathematical processing.

More Lessons In This Unit

Browse all guides in the Year 10 Science guide library.