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)
