• # question_answer The solubility of iodine in water increases in the presence of [CPMT 1973, 74, 78, 86, 89, 91; NCERT 1973; AFMC 1995] A) Alcohol B) Chloroform C) Sodium hydroxide D) Potassium iodide

Iodine has the least affinity for water and is only slightly soluble in it. However, it dissolves in 10% aq. solution of KI due to the formation of a complex ion i.e. $2NaCl+2{{H}_{2}}O\,\,\to \,\,2NaOH+\underset{\text{(anode)}}{\mathop{C{{l}_{2}}}}\,+\underset{\text{(cathode)}}{\mathop{{{H}_{2}}}}\,$.        ${{I}_{2}}+KI$ ⇌$2{{F}_{2}}+2{{H}_{2}}O\,\to \,4HF+{{O}_{2}}$ or   ${{I}_{2}}+{{I}^{-}}$ ⇌ $I_{3}^{-}$ (complex ion)