CAIE A Level Chemistry 9701 · Chemical energetics
A sealed flask contains gaseous water at 120 °C. The flask is cooled to 90 °C, and the water condenses to a liquid. In terms of the arrangements of the particles and their energy, explain why the entropy of the water decreases during this cooling and condensation.
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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