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GCSE Chemistry · key term
The amount of exposed surface available for contact with another substance.
Used by OCR
Specification C2.3h · Paper 1 (Foundation), Paper 3 (Higher)
Revise: Surface Area to Volume RatioThe smaller pieces should finish fizzing sooner because they provide a greater exposed surface area for contact with the water. Repeats allow a mean time to be calculated and make the comparison more reliable.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
The total area of a solid that is exposed to a substance it can react with.
Revise: Surface area explanationConversely, using larger pieces reduces the exposed surface area to volume ratio and slows the reaction.
For a rate explanation, link the steps clearly: smaller pieces → larger total exposed surface area → more frequent successful collisions → faster reaction.
Do not say that crushing increases the amount or volume of solid. If none is lost, its total mass and volume remain the same; it is the exposed surface area that increases.
Explain the full chain: smaller pieces → greater exposed surface area to volume ratio → more frequent successful collisions → faster reaction.
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