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CAIE A Level Chemistry 9701 · Group 2

Group 2: describe question

Describe6 marksChallenge

A student investigates the reaction of magnesium with steam. A sample of magnesium ribbon is heated strongly in a stream of steam. The student observes a bright white flame and a white solid is formed.

(a) Write an equation for the reaction of magnesium with steam.

(b) The student repeats the experiment with calcium. Predict, with a reason, how the vigour of the reaction with steam compares with that of magnesium.

(c) The student also heats a sample of magnesium carbonate strongly. State what is observed and write an equation for the reaction. Explain, in terms of the metal ion, why magnesium carbonate is less thermally stable than barium carbonate.

0 words · 6 marks

No account needed for your first marks. Your answer is used only to mark it.

How this question is marked

6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.

Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.

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