Chemistry · May / June 2023 · Paper 41 · Question 6
0620
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This question is about sulfur and compounds of sulfur. Sulfur is converted into sulfuric acid, H2SO4, by the Contact process. The process involves four stages. stage 1 Molten sulfur is converted into sulfur dioxide. stage 2 Sulfur dioxide reacts with oxygen to form sulfur trioxide. stage 3 Sulfur trioxide combines with concentrated sulfuric acid to form oleum, H2S2O7. stage 4 Oleum reacts to form concentrated sulfuric acid.
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6(a)(i)[1]
4FeS2 + 11O2 → 2Fe2O3 + 8SO2
6(a)(ii)[1]
iron(III) oxide
6(b)(i)[1]
yield of SO3 is less
6(b)(ii)[1]
yield of SO3 is less
OR
rate is less
6(c)[2]
2NH3 + H2SO4 →(NH4)2SO4
M1 (NH4)2SO4 on the right (1)
M2 equation correct(1)
6(d)(i)[1]
lead(II) nitrate
6(d)(ii)[3]
Pb2+ (aq) +SO42-(aq) → PbSO4(s)
M1 PbSO4 on the right(1)
M2 only Pb2+ and SO42– on the left(1)
M3(aq) + (aq) → (s)(1)
6(d)(iii)[3]
M1 filter(1)
M2 wash (the residue or lead sulfate) with distilled or deionised water(1)
M3 description of drying(1)
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