P-Block Elements Ques 85

Question: The solubility of iodine in water increases in the presence of

[CPMT 1973, 74, 78, 86, 89, 91; NCERT 1973; AFMC 1995]

Options:

A) Alcohol

B) Chloroform

C) Sodium hydroxide

D) Potassium iodide

Show Answer

Answer:

Correct Answer: D

Solution:

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+2H_2O\to 2NaOH+\underset{\text{(anode)}}{\mathop{Cl_2}}+\underset{\text{(cathode)}}{\mathop{H_2}} $ . $ I_2+KI $ ⇌ $ 2F_2+2H_2O\to 4HF+O_2 $ or $ I_2+{{I}^{-}} $ ⇌ $ I_3^{-} $ (complex ion)



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