Question

Give the chemical tests to distinguish between the following gases:

Chlorine and nitrogen dioxide

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 Chlorine and nitrogen dioxide are as follows:

Name of the test	Chlorine $\left({\mathrm{Cl}}_2\right)$	Nitrogen dioxide $\left({\mathrm{NO}}_2\right)$
Reaction with Silver nitrate solution	Chlorine gas reacts with Silver nitrate solution to form white precipitates of Silver chloride as shown below.$\underset{(\mathrm{Silver}\mathrm{nitrate})}{4{\mathrm{AgNO}}_3\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Chlorine}\right)}{2{\mathrm{Cl}}_2\left(\mathrm{g}\right)}\to \underset{(\mathrm{Silver}\mathrm{chloride})}{4\mathrm{AgCl}\left(\mathrm{s}\right)}+\underset{(\mathrm{Dinitrogen}\mathrm{pentoxide})}{2{\mathrm{N}}_2{\mathrm{O}}_5\left(\mathrm{g}\right)}+\underset{\left(\mathrm{Oxygen}\right)}{{\mathrm{O}}_2\left(\mathrm{g}\right)}$	Nitrogen dioxide does not react with silver chloride and hence no white precipitates are formed.