Explain4 marksStandard
The decomposition of calcium carbonate is represented by the equation:
For this reaction, and .
The reaction is not feasible at but becomes feasible at high temperatures.
Use the Gibbs equation to explain this observation.
CAIE A Level Chemistry 9701 · Chemical energetics
Chemical energetics: explain question
How this question is marked
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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