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GCSE Chemistry · key term
The physical change from a liquid to a gas throughout the liquid at its boiling point.
Used by AQA, Edexcel and OCR
Specification 4.2.2.1 · Paper 1
The change of state from a liquid to a gas throughout the liquid, with bubbles forming.
Revise: States of MatterBoiling is the change from liquid to gas throughout the liquid; the reverse process is condensing. Both take place at the boiling point.
Specification 2.2 · Paper 1
Revise: Interconversions Between StatesFreezing reverses melting, condensation reverses evaporation or boiling, and deposition reverses sublimation. Familiar water provides several examples: ice melts to form liquid water, liquid water freezes to form ice, and water vapour condenses into liquid droplets on a cold window.
Specification C1.1a · Paper 1 (Foundation), Paper 3 (Higher)
The change from the liquid state to the gas state throughout a liquid, producing bubbles.
Revise: Features of the Particle ModelDuring boiling, gas forms throughout the liquid, producing bubbles, and the liquid changes to the gas state. The bubbles contain the substance in its gas state—for example, bubbles in boiling water contain water vapour rather than air or separate hydrogen and oxygen.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
The change from liquid to gas throughout a liquid when it reaches its boiling point.
Revise: The particle modelProperties such as state, boiling point, colour and electrical conductivity describe a large sample containing enormous numbers of particles. They do not normally describe one isolated particle.
The transfer of energy to a liquid that allows gas to form throughout the liquid at its boiling point.
When given melting and boiling points, compare the temperature with both values rather than relying on the substance's usual state at room temperature.
Use the direction of energy transfer: energy is transferred to the substance during melting and boiling, and from the substance during freezing and condensing.
Refer to forces between particles unless the structure means that chemical bonds themselves must be overcome. For a simple molecular substance, boiling overcomes intermolecular forces, not the covalent bonds within its molecules.
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