Question

Large-scale manufacture of nitric acid by Ostawald process utilizes the reaction-

• A. $2NaN{O}_3+H_{2}S{O}_4\to N{a}_{2}S{O}_4+2HN{O}_3$
• B. $4N{H}_3+5O_2\to 4NO+6H_{2}O$
• C. $N{O}_2^{+}+N{O}_3^{-}+H_{2}O\to 2HN{O}_3$
• D. $2NO+O_2+H_{2}O\to HN{O}_3+HN{O}_2$

Answer 1

The correct option is B $4N{H}_3+5O_2\to 4NO+6H_{2}O$

The balanced chemical equation involved in manufacturing of $HN{O}_3$ by Ostwald's process are shown as:

Step 1 Formation of nitric oxide (NO)
$4N{H}_3\left(g\right)+5O_2\left(g\right)\underset{\text{500K, 9bar}}{\overset{\text{Pt/Rh, gases~ catalyst}}{\to }}4NO\left(g\right)+6H_{2}O$

Step 2 Formation of nitrogen dioxide $\left(N{O}_2\right)$
$2NO\left(g\right)+O_2\left(g\right)\to 2N{O}_2\left(g\right)$

Step 3 Absorption of $N{O}_2$ (Formation of $HN{O}_3$)
$3N{O}_2\left(g\right)+H_{2}O\to 2HN{O}_3\left(l\right)+NO\left(g\right)$
Therefore, the correct option is (b).