Question

Assertion
For drying ammonia gas, the common dehydrating agents like ${{H}_{2}}S{{O}_{4}},CaC{{l}_{2}}\ \text{or }{{\text{P}}_{\text{2}}}{{\text{O}}_{\text{5}}}$ can-not be used
Reason
${{H}_{2}}S{{O}_{4}},CaC{{l}_{2}}\ \text{or }{{\text{P}}_{\text{2}}}{{\text{O}}_{\text{5}}}$ react with $N{{H}_{3}}$
A. Both assertion and reason are correct and reason is the correct explanation of assertion.
B. Both assertion and reason are correct but reason is not the correct explanation of assertion.
C. Assertion is correct but reason is not correct.
D. Both assertion and reason are incorrect.

Answer 1

Hint: Ammonia is a compound composed of nitrogen and hydrogen represented by the chemical formula $N{{H}_{3}}$. It is a colorless gas with a pungent smell. Ammonia gas is produced by the process known as Haber’s process.

Complete step by step answer:
- Most common dehydrating agents are ${{H}_{2}}S{{O}_{4}},CaC{{l}_{2}}\ \text{or }{{\text{P}}_{\text{2}}}{{\text{O}}_{\text{5}}}$ but they can-not be used in drying ammonia this can be explained by the following manner.
- Ammonia can-not be dried by passing concentrated sulphuric acid represented by ${{H}_{2}}S{{O}_{4}}$ because ammonia reacts with concentrated sulphuric acid and form ammonium sulphate. Its reaction can be shown as:
$2N{{H}_{3}}+{{H}_{2}}S{{O}_{4}}\to {{(N{{H}_{4}})}_{2}}S{{O}_{4}}$
- Ammonia also reacts with calcium chloride represented by $CaC{{l}_{2}}$ or ${{\text{P}}_{\text{2}}}{{\text{O}}_{\text{5}}}$ and forms an addition compound with anhydrous calcium chloride which can be shown as follows:
$8N{{H}_{3}}+CaC{{l}_{2}}\to CaC{{l}_{2}}.8N{{H}_{3}}$ (Additional compound)
Hence it will not dried with $CaC{{l}_{2}}$ or ${{\text{P}}_{\text{2}}}{{\text{O}}_{\text{5}}}$. In both the cases $N{{H}_{3}}$ reacts with the compound so we can say that both assertion and reason are correct and reason is the explanation of assertion.
The correct answer is option “A” .

Note: Dehydrating agents can be defined as those substances which are used to dry or remove water from the material. Any chemical reaction in which dehydration occurs the reacting molecules loses a molecule of water.