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) $15 \mathrm{CaO}+4 \mathrm{P} _{4} \stackrel{\Delta}{\longrightarrow} 5 \mathrm{Ca} _{3} \mathrm{P} _{2}+3 \mathrm{P} _{2} \mathrm{O} _{5} \uparrow$
$\left[\mathrm{Ca} _{3} \mathrm{P} _{2}+6 \mathrm{H} _{2} \mathrm{O} \longrightarrow 3 \mathrm{Ca}(\mathrm{OH}) _{2}+2 \mathrm{PH} _{3} \uparrow\right] \times 5$
$ \overline{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
$\overline{\mathrm{CaSO} _{4}+2 \mathrm{NH} _{3}+\mathrm{CO} _{2}+\mathrm{H} _{2} \mathrm{O} \longrightarrow \mathrm{CaCO} _{3} \downarrow+\left(\mathrm{NH} _{4}\right) _{2} \mathrm{SO} _{4}}$
