Chemistry · Oct / Nov 2022 · Paper 42 · Question 4
0620
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The question as text
A student prepares magnesium sulfate crystals, MgSO4, by adding excess magnesium to dilute sulfuric acid.
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4(a)[1]
Mg + H2SO4 → MgSO4 + H2
4(b)[2]
M1 no (more) fizzing (1)
M2 solid stops dissolving or a solid remains / is visible (in the mixture) (1)
4(c)[1]
residue
4(d)(i)[1]
saturated
4(d)(ii)[1]
solubility (of MgSO4 / solid) decreases (as temperature decreases)
4(e)(i)[1]
hydrated
4(e)(ii)[3]
M1 Mr MgSO4 = 120 (1)
M2 mol MgSO4 = 2.40 / M1 = 2.40 / 120 = 0.02(00) (1)
M3 0.02(00) / 0.02(00) = 1
0.140 / 0.02(00) = 7 and x = 7 (1)
4(f)[2]
2Mg(NO3)2 → 2MgO + 4NO2 + O2
M1 NO2 + O2 (1)
M2 equation completely correct (1)
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