Sulphur trioxide can be obtained by which of the following reactions?
- CaSO4 + C
- Fe2(SO4)3
- S + H2SO4
- H2SO4 + PCl5
Answer
(2) Fe2(SO4)3
Solution
Ferric sulphate decomposes on heating to give sulphur trioxide:
Fe2(SO4)3 Fe2O3 + 3SO3
The other reactions do not give it:
CaSO4 + 2C CaS + 2CO2
S + 2H2SO4 3SO2 + 2H2O
H2SO4 + 2PCl5 SO2Cl2 + 2POCl3 + 2HCl
Answer: (2)