Question

Quantitatively the estimation of ozone can be done by which of the following process?

• A. Decomposition into $O_{2}$ and absorption of $O_{2}$ into pyrogallol.
• B. Volumetric method using $KI$ and titration of
  the liberated iodine using hypo solution.
• C. Oxidative ozonolysis method.
• D. All methods given above.

Answer 1

Answer: (B)

$2KI+H_{2}O+O_{3} \rightarrow 2KOH+O_{2}+I_{2}$
$2S_{2}O_{3}^{2 -}+I_{2} \rightarrow S_{4}O_{6}^{2 -}+2I^{-}$
1 mole of $O_{3}=1$ mole of $I_{2}=2$ mole of $S_{2}O_{3}^{2 -}$