Question

How will you prove that hydrochloric acid contains

1. hydrogen
2. chlorine?

Write equations for the reactions.

Answer 1

We can prove that hydrochloric acid contains both hydrogen and chlorine by the following experiment:

Take a voltameter used for water electrolysis with a platinum cathode and a graphite anode. Pour 4 molars of \[\ce{HCl}\] into the voltameter and measure the direct electric current. The cathode emits a colorless gas, while the anode produces a greenish-yellow gas. If you put a burned splinter close to a colorless gas, the gas will burst into flames, showing that it is hydrogen gas. It is clear that the gas is chlorine because when wet starch iodide paper is put in it, it turns blue-black.

Chemical equation: \[\ce{2HCl ->  H2 ^ + Cl2 ^}\]

This experiment proves that hydrochloric acid contains both hydrogen and chlorine.