During the layer test for halogens, addition of chlorine water to a mixture of an unknown salt and c — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Chlorine oxidises $I^-$ to $I_2$, which gives a violet colour in chloroform. Excess $Cl_2$ further oxidises the $I_2$ to colourless iodic acid ($HIO_3$), causing the colour to disappear. Bromine forms a brown layer that does not fade as easily.