How is nitric acid manufactured by Ostwald’s process? How does it reacts with the following.
a) Cu b) Zn c) S₈ d) P₄

Ostwald’s Process:
1) Step I: Ammonia is oxidized by air in the presence of Pt catalyst at 800oC to give nitric oxide.
$4{\mathrm{NH}}_3+5{\mathrm{O}}_2\underset{800°\mathrm{C},6-7 \mathrm{atm} }{\overset{\mathrm{Pt}/\mathrm{Rh}}{\rightleftharpoons }}4\mathrm{NO}+6{\mathrm{H}}_2\mathrm{O}$
2) Step II: NO is oxidized to NO₂ by air at a temperature below 100°C.
$2\mathrm{NO}+{\mathrm{O}}_2\stackrel{<{100}^{\circ }\mathrm{C}}{\to }2{\mathrm{NO}}_2$
3) Step III: NO₂ is dissolved in water in the presence of oxygen HNO₃ is formed.
$4{\mathrm{NO}}_2+2{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2\stackrel{ }{\to }4{\mathrm{HNO}}_3$
Concentration: HNO₃ is concentrated by
1. Distillation - then 68.5% HNO₃ is formed.
2. Dehydration - then 98% HNO₃ is formed with conc. H₂SO₄
$\text{ a) }\mathrm{Cu}+4{\mathrm{HNO}}_3\to \mathrm{Cu}{\left({\mathrm{NO}}_3\right)}_2+2{\mathrm{NO}}_2+2{\mathrm{H}}_2\mathrm{O}$
$\text{ b) }\mathrm{Zn}+4{\mathrm{HNO}}_3\to \mathrm{Zn}{\left({\mathrm{NO}}_3\right)}_2+2{\mathrm{NO}}_2+2{\mathrm{H}}_2\mathrm{O}$
$\text{ c) }{\mathrm{S}}_8+48{\mathrm{HNO}}_3\to 8{\mathrm{H}}_2{\mathrm{SO}}_4+48{\mathrm{NO}}_2+16{\mathrm{H}}_2\mathrm{O}$
$\text{ d) }{\mathrm{P}}_4+20{\mathrm{HNO}}_3\to 4{\mathrm{H}}_3{\mathrm{PO}}_4+20{\mathrm{NO}}_2+4{\mathrm{H}}_2\mathrm{O}$