Chemistry · May / June 2020 · Paper 42 · Question 3
0620
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3(a)(i)[1]
heat in air
3(a)(ii)[3]
2SO2 + O2 → 2SO3 (1)
450°C (1)
vanadium(V) oxide (1)
3(a)(iii)[2]
rate of forward reaction and rate of backward reaction are equal (1)
concentrations of reactants and products are constant (1)
3(b)[1]
concentrated sulfuric acid
3(c)[2]
H2S2O7 + H2O →2H2SO4
3(d)[1]
Cu + 2H2SO4 →CuSO4 + SO2 + 2H2O
3(e)[1]
purple to colourless
3(f)[2]
2NH3 + H2SO4 →(NH4)2SO4
3(g)(i)[1]
barium nitrate / barium chloride
3(g)(ii)[2]
Ba2+(aq) + SO42-(aq) → BaSO4(s)
formulae (1) state symbols (1)
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