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O-Level Acid-Base Chemistry: worked solution
2 marks. Full working, one step per line.
Question
Epsom salt has a bitter taste and the formula MgSO4.nH2O. It is commonly added to bath water to ease aching muscles. Propose the chemical formulae of two suitable reactants that could be used to prepare aqueous magnesium sulfate, and state which of the two is used in excess. [2]
Worked answer
Aqueous magnesium sulfate is made by reacting an insoluble base/carbonate with dilute sulfuric acid, e.g. magnesium oxide (or MgCO3 / Mg(OH)2) with sulfuric acid: MgO + H2SO4 -> MgSO4 + H2O. The solid MgO is added in excess so that all the acid is used up; the leftover solid is then filtered off.
Practise this topic
This question is part of O-Level Acid-Base Chemistry, in O-Level Pure Chemistry.