Question

Identify the following substance that is underlined: The Catalyst used to oxidize ammonia.

Answer 1

Catalyst: A catalyst is a chemical species that increase the rate of reaction without taking part in the chemical reaction.

Catalytic oxidation of ammonia:

• Ammonia when heated at temperature $800°\mathrm{C}$, in the presence of platinum $\left(\mathrm{Pt}\right)$ catalyst, leads to the formations of Nitric oxide $\left(\mathrm{NO}\right)$, and water.
• A large amount of heat is liberated during the reaction.
• The balanced chemical reaction can be represented as:

$\underset{\mathrm{Ammonia}\mathrm{gas}}{4{\mathrm{NH}}_3\left(\mathrm{g}\right)}+\underset{\mathrm{Oxygen}\mathrm{gas}}{5{\mathrm{O}}_2\left(\mathrm{g}\right)}\stackrel{\mathrm{Pt},800°\mathrm{C}}{\to }\underset{\mathrm{Water}}{6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)}+\underset{\mathrm{Nitric}\mathrm{oxide}}{4\mathrm{NO}\left(\mathrm{g}\right)}+\mathrm{Heat}$

• Nitric oxide is further oxidized to give brown fumes of Nitrogen dioxide gas.
• The balanced chemical reaction can be represented as:

$\underset{\mathrm{Nitric}\mathrm{oxide}}{2\mathrm{NO}\left(\mathrm{g}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Nitrogen}\mathrm{dioxide}}{2{\mathrm{NO}}_2\left(\mathrm{g}\right)}$

So, The Catalyst used to oxidize ammonia is platinum.