CAIE A Level Chemistry 9701 · Atoms, molecules and stoichiometry
Anhydrous iron(III) sulfate forms a hydrated salt with the formula .
(a) Explain, in terms of the ions present, why the formula of the anhydrous salt is and not or .
(b) Explain what is meant by the terms hydrated, anhydrous and water of crystallisation.
(c) Write a balanced equation, with state symbols, for the dehydration of the hydrated salt.
(d) Explain whether the formula is an empirical formula or a molecular formula, and justify your answer.
5 marks, so the mark scheme is looking for about 5 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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