Question

Yellow coloured solution of ${FeCl}_3$ changes to light green when:

• A. ${SnCl}_2$ is added
• B. $Zn$ is added
• C. $H_{2}S$ gas is passed
• D. All of the above

Answer 1

The correct option is D All of the above

The ferric chloride solution is yellow in colour whereas ferrous chloride solution is light green in colour.
$H_{2}S$ reduces Fe(III) ions to Fe(II) ions.
$2F{e}^{3+}+S^{2-}\to 2F{e}^{2+}+S$
Hence, yellow solution turns into light green solution.This reduction can also be carried out by the addition of zinc or stannous chloride.