Question

Give the chemical tests to distinguish between the following gases:

Hydrogen chloride and Hydrogen sulphide

Answer 1

• Chemical tests include the chemical reactions of the gases with other chemicals that help us to confirm the gas.
• Physical tests like colour and odour are also helpful but do not help to confirm the gas.
• Chemical tests to distinguish Hydrogen chloride and Hydrogen sulphide are as follows:

Name of the test	Hydrogen chloride $\left(\mathrm{HCl}\right)$	Hydrogen sulphide $\left({\mathrm{H}}_2\mathrm{S}\right)$
Lead acetate paper test	It does not turn lead acetate paper black.	It turns lead acetate paper black. $$\begin{gathered} {\left({\mathrm{CH}}_3\mathrm{COO}\right)}_2\mathrm{Pb}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)\to \mathrm{PbS}\left(\mathrm{s}\right)+2{\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right) \\ (\mathrm{Lead}\mathrm{acetate})(\mathrm{Hydrogen}\mathrm{sulphide})(\mathrm{Lead}\mathrm{sulphide})(\mathrm{Acetic}\mathrm{acid}) \\ \left(\mathrm{black}\right) \end{gathered}$$
Reaction with Ammonia	When a rod dipped in ammonia is brought near Hydrochloric acid, dense white fumes or smog of Ammonium chloride are produced. $$\begin{gathered} {\mathrm{NH}}_3\left(\mathrm{aq}\right)+\mathrm{HCl}\left(\mathrm{g}\right)\to {\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{s}\right) \\ \left(\mathrm{Ammonia}\right)(\mathrm{Hydrochloric}\mathrm{acid})(\mathrm{Ammonium}\mathrm{chloride}) \\ (\mathrm{white}\mathrm{fumes}) \end{gathered}$$	It does not react with Ammonia to produce dense white fumes.