Q89 / 200 · NEET 2012 (Screening) · Chemistry
Sulphur trioxide can be obtained by which of the following reaction
- A$\mathrm{CaSO}_4+\mathrm{C} \stackrel{\Delta}{\longrightarrow}$
- Correct answerB$\mathrm{Fe}_2\left(\mathrm{SO}_4\right)_3 \stackrel{\Delta}{\longrightarrow}$
- C$\mathrm{S}+\mathrm{H}_2 \mathrm{SO}_4 \stackrel{\Delta}{\longrightarrow}$
- D$\mathrm{H}_2 \mathrm{SO}_4+\mathrm{PCl}_5 \stackrel{\Delta}{\longrightarrow}$
Solution
$\text {(a) } \mathrm{CaSO}_4+\mathrm{C} \stackrel{\Delta}{\longrightarrow} \mathrm{CaO}+\mathrm{SO}_2+\mathrm{CO}$
(b) $\mathrm{Fe}_2\left(\mathrm{SO}_4\right)_3 \stackrel{\Delta}{\longrightarrow} \mathrm{Fe}_2 \mathrm{O}_3+3 \mathrm{SO}_3$
(c) $\mathrm{S}+2 \mathrm{H}_2 \mathrm{SO}_4 \stackrel{\Delta}{\longrightarrow} 3 \mathrm{SO}_2+2 \mathrm{H}_2 \mathrm{O}$
(d) $\mathrm{H}_2 \mathrm{SO}_4+\mathrm{PCl}_5 \stackrel{\Delta}{\longrightarrow} \mathrm{SO}_3 \mathrm{HCl}+\mathrm{POCl}_3+\mathrm{HCl}$
$\mathrm{SO}_3 \mathrm{HCl}$ is chloro sulphonic acid
Thus, $\mathrm{SO}_3$ is obtained by heating $\mathrm{Fe}_2\left(\mathrm{SO}_4\right)_3$.
Hence, the correct answer is option: 'B'.