Question

Give the chemical tests to distinguish between the following gases:

Ammonia and hydrogen chloride

Answer 1

In practical Chemistry, two types of analysis are done.

1. Qualitative analysis: The analysis which aims at detecting the presence of any substance in a given sample.
2. Quantitative analysis: The analysis which aims at knowing the quantity of any substance present in a sample.

These chemical tests include the chemical reactions of the gases with other chemicals that help us to confirm the gas by qualitative analysis.

• Physical tests like colour and odour are also helpful but do not help to confirm the gas.
• Chemical tests to distinguish between Ammonia and Hydrogen chloride are as follows:

Name of the test	Ammonia $\left({\mathrm{NH}}_3\right)$	Hydrogen chloride $\left(\mathrm{HCl}\right)$
Reaction with litmus	Ammonia gas turns moist red litmus paper blue as it is basic in nature.	Hydrogen chloride gas turns moist blue litmus paper red as it is acidic in nature.
Reaction with Silver nitrate $\left({\mathrm{AgNO}}_3\right)$	It does not react with Silver nitrate.	It reacts with Silver nitrate to form white precipitates of Silver chloride.$\underset{(\mathrm{Silver}\mathrm{nitrate})}{{\mathrm{AgNO}}_3\left(\mathrm{aq}\right)}+\underset{(\mathrm{Hydrochloric}\mathrm{acid})}{\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{(\mathrm{Silver}\mathrm{chloride})}{\mathrm{AgCl}\left(\mathrm{s}\right)}+\underset{(\mathrm{Nitric}\mathrm{acid})}{{\mathrm{HNO}}_3\left(\mathrm{aq}\right)}$