If hydrogen sulphide gas is passed into a solution of a pure iron chloride, a ye...

When hydrogen sulphide gas (\(H_2S\) is passed into a solution of pure iron chloride, a chemical reaction occurs. This reaction can be represented by the following equation:

\(2FeCl_3 + 3H_2S → Fe_2S_3(s) + 6HCl\)

In this reaction, iron (III) chloride (\(FeCl_3\) reacts with hydrogen sulphide to form a yellow deposit of iron (III) sulphide (\(Fe_2S_3\) and hydrochloric acid (\(HCl\).

When the yellow deposit of iron (III) sulphide is filtered, the remaining pale green solution is a result of the remaining iron (III) chloride reacting with water. This reaction can be represented by the following equation:

\(FeCl_3 + 3H_2O → Fe(OH)_3(s) + 3HCl\)

In this reaction, iron (III) chloride reacts with water to form a pale green precipitate of iron (III) hydroxide (\(Fe(OH)_3\) and hydrochloric acid. The hydrochloric acid will then react with the iron (III) hydroxide to form iron (II) chloride (\(FeCl_2\).

Therefore, the pale green solution is iron (II) chloride.