CAIE A Level Chemistry 9701 · Atoms, molecules and stoichiometry
Calcium nitrate crystallises from water as the hydrated salt .
(a) Explain how the formula of the anhydrous salt, , follows from the charges on the calcium and nitrate ions.
(b) Explain what is meant by water of crystallisation, and by the terms hydrated and anhydrous.
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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