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 HCl into the voltameter and measure the direct electric current. The cathode emits a colourless gas, while the anode produces a greenish-yellow one. If you put a burned splinter close to a colourless gas, the gas will burst into flames, showing that it is hydrogen gas. Wet starch iodide paper turns blue-black when immersed in the gas, confirming its identity as chlorine.

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

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