Making soluble salts (except sodium, potassium and ammonium salts)
3 marks · EasyHydrated magnesium sulfate crystals can be prepared using magnesium and dilute sulfuric acid.
Write the balanced symbol equation for the reaction.
State the gaseous product formed.
Write the equation for the crystallisation reaction to form hydrated magnesium sulfate.
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(a) \ce{Mg(s) + H2SO4(aq) -> MgSO4(aq) + H2(g)}
(b) Hydrogen / H2
(c) \ce{MgSO4(aq) + 7H2O(l) -> MgSO4.7H2O(s)}
Common mistakes: Wrong formula for magnesium sulfate or omission of hydrogen gas.; Not including water in the crystallisation reaction.
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Marking points
A1 (a) · 1 mark · Correct balanced symbol equation for reaction.
B1 (b) · 1 mark · Correctly states hydrogen / H2 as the gaseous product.
C1 (c) · 1 mark · Correct crystallisation equation, forming hydrated salt.
Worked solution
(a) \ce{Mg(s) + H2SO4(aq) -> MgSO4(aq) + H2(g)}
(b) Hydrogen gas, \ce{H2}
(c) \ce{MgSO4(aq) + 7H2O(l) -> MgSO4.7H2O(s)}