pBlock ElementsII 1 Question 87
83. Write balanced equations for the following.
(i) Phosphorus is treated with concentrated nitric acid.
(ii) Oxidation of hydrogen peroxide with potassium permanganate in acidic medium.
(iii) Manufacture of phosphoric acid from phosphorus.
(iv) Reaction of aluminium with aqueous sodium hydroxide.
$(1997,1 \mathrm{M} \times 4=4 \mathrm{M})$
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Solution:
- (i) $\mathrm{P}{4}+20 \mathrm{HNO}{3} \longrightarrow 4 \mathrm{H}{3} \mathrm{PO}{4}+20 \mathrm{NO}{2}+4 \mathrm{H}{2} \mathrm{O}$
(ii) $3 \mathrm{KMnO}{4}+5 \mathrm{H}{2} \mathrm{O}{2}+3 \mathrm{H}{2} \mathrm{SO}{4} \longrightarrow \mathrm{K}{2} \mathrm{SO}_{4}$
$$ +2 \mathrm{MnSO}{4}+5 \mathrm{O}{2}+8 \mathrm{H}_{2} \mathrm{O} $$
(iii) $\mathrm{P}{4}+20 \mathrm{HNO}{3} \longrightarrow 4 \mathrm{H}{3} \mathrm{PO}{4}+20 \mathrm{NO}{2}+4 \mathrm{H}{2} \mathrm{O}$
(iv) $2 \mathrm{Al}+2 \mathrm{NaOH}+2 \mathrm{H}{2} \mathrm{O} \longrightarrow 2 \mathrm{NaAlO}{2}+3 \mathrm{H}_{2}$
