pBlock ElementsII 1 Question 99
95. Draw balanced equations for
(i) the preparation of phosphine from $\mathrm{CaO}$ and white phosphorus.
(ii) the preparation of ammonium sulphate from gypsum, ammonia and carbon dioxide.
$(1990,2 \mathrm{M})$
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Solution:
- (i) $15 \mathrm{CaO}+4 \mathrm{P}{4} \stackrel{\Delta}{\longrightarrow} 5 \mathrm{Ca}{3} \mathrm{P}{2}+3 \mathrm{P}{2} \mathrm{O}_{5} \uparrow$
$\left[\mathrm{Ca}{3} \mathrm{P}{2}+6 \mathrm{H}{2} \mathrm{O} \longrightarrow 3 \mathrm{Ca}(\mathrm{OH}){2}+2 \mathrm{PH}_{3} \uparrow\right] \times 5$
$15 \mathrm{CaO}+4 \mathrm{P}{4}+30 \mathrm{H}{2} \mathrm{O} \longrightarrow 15 \mathrm{Ca}(\mathrm{OH})_{2}$
$$ +3 \mathrm{P}{2} \mathrm{O}{5} \uparrow+10 \mathrm{PH}_{3} \uparrow $$
(ii) $2 \mathrm{NH}{3}+\mathrm{CO}{2}+\mathrm{H}{2} \mathrm{O} \longrightarrow\left(\mathrm{NH}{4}\right){2} \mathrm{CO}{3}$ $\mathrm{CaSO}{4}+\left(\mathrm{NH}{4}\right){2} \mathrm{CO}{3} \longrightarrow \mathrm{CaCO}{3} \downarrow+\left(\mathrm{NH}{4}\right){2} \mathrm{SO}{4}$ gypsum
$\overline{\mathrm{CaSO}{4}+2 \mathrm{NH}{3}+\mathrm{CO}{2}+\mathrm{H}{2} \mathrm{O} \longrightarrow \mathrm{CaCO}{3} \downarrow+\left(\mathrm{NH}{4}\right){2} \mathrm{SO}{4}}$
