Question

What is the catalyst used in the industrial manufacture of nitric acid?

• A. Powdered iron (III) oxide
• B. Vanadium (V) oxide
• C. Zinc-mercury amalgam
• D. Platinum-Rhodium gauge sheet

Answer 1

The correct option is D Platinum-Rhodium gauge sheet

Ostwald’s process is the industrial process to manufacture nitric acid in bulk.
Step $1$: The first step involves the oxidation of ammonia which forms nitric oxide.
$4N{H}_3\left(g\right)+5O_2\left(g\right)\underset{500K,9bar}{\overset{Pt/Rhgaugecatalyst}{\to }}4NO\left(g\right)+6H_{2}O\left(g\right)$
Step $2$: The nitric oxide so formed, combines with oxygen to give $N{O}_2$.
$2NO\left(g\right)+O_2\left(g\right)\to 2N{O}_2\left(g\right)$
Step $3$: Subsequently, nitrogen dioxide is dissolved in water to produce adequate concentrations of nitric acid.
$3N{O}_2\left(g\right)+H_{2}O\left(l\right)\to 2HN{O}_3\left(aq\right)+NO\left(g\right)$