Question

Give one test to distinguish between the following pair of chemicals.
Iron (III) Chloride solution and copper chloride solution.

Answer 1

Iron (III) chloride solution and copper chloride solution can be distinguished by using ammonium hydroxide. Copper forms a blue ppt. of Cu(OH)2 which is soluble in excess of ammonium hydroxide.
\[\ce{CuCl2 + 2NH4OH -> Cu(OH)2 + 2NH4Cl}\]

Whereas iron(III) forms a reddish brown ppt. of Fe(OH)₃ which is insoluble even in excess of ammonium hydroxide.
\[\ce{FeCl3 + 3NH4OH -> Fe(OH)3 + 3NH4Cl}\]