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GCSE Chemistry · key term
The observable point chosen to mark when a particular stage of a reaction has been reached.
Used by OCR
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Revise: Determining rate of reactionStart a stopwatch when the reactants are mixed, then take readings at regular intervals or time a clearly defined endpoint.
An observable point chosen to stop timing a reaction, such as a specified colour change.
When comparing times for a colour or disappearing-cross endpoint, use the same endpoint and viewing conditions each time.
A colour-change endpoint must be judged in the same way each time; do not claim that a stopwatch measures the colour directly.
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