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

Conservation of mass

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 describe what happens to the atoms of reactants as they form products in a chemical reaction.

Key Notes

  • Atoms are the building blocks that can be combined in different ways to form different substances.
  • It is impossible for any atom to be changed into a different type of atom by a chemical reaction.
  • All of the atoms in the reactants of a chemical reaction are reorganised to form all of the products of the reaction.
  • It is impossible to make a particular product without all the atoms that it needs.
  • The law of conservation of mass can be applied to a closed system, or a non-enclosed system that takes in/gives out gas.

Vocabulary To Learn

  • conservation of mass: Conservation of mass means that the combined mass of the starting reactants equals the combined mass of the products formed.
  • closed system: A closed system is one in which matter cannot enter or leave the observed environment, allowing only energy transfer between the system and its surrounding environment.
  • reactant: Reactants are the elements or compounds before a reaction takes place.
  • product: Products are the elements or compounds that are formed after a reaction has taken place.
  • atom: Atoms are the building blocks of all matter.

Common Mistakes To Avoid

  • Pupils can struggle to link chemical formulae to what is happening on the atomic level and to what they observe during a chemical reaction.

3 Quick Questions (With Answers)

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

Atoms are the building blocks that can be combined in different ways to form different substances. It is impossible for any atom to be changed into a different type of atom by a chemical reaction.

2. Define this scientific word and use it in context. 'conservation of mass'

Conservation of mass means that the combined mass of the starting reactants equals the combined mass of the products formed. Include the word in a full scientific explanation, not as a single label.

3. Correct this common scientific misunderstanding.

Mistake: Pupils can struggle to link chemical formulae to what is happening on the atomic level and to what they observe during a chemical reaction. Correction: Reinforce via demonstrations, modelling and diagrams via Johnstone's triangle. One simple demo (e.g. magnesium + oxygen) = one model, one diagram and one chemical reaction equation. Use progressively more complicated demos and build up from there.

More Lessons In This Unit

Browse all guides in the Year 10 Science guide library.