Ozone is passed into excess neutral potassium iodide solution: O3 + 2I- + H2O -> I2 + O2 + 2OH-. The iodine is titrated with sodium thiosulphate, I2 + 2S2O3^2- -> 2I- + S4O6^2-. How many moles of Na2S2O3 are consumed per mole of O3?

JEE Main levelSingle correct optionDifficulty 2 of 3pn063

Ozone is passed into excess neutral potassium iodide solution: $O X_{3} + 2 I X^{-} + H X_{2} O I X_{2} + O X_{2} + 2 OH X^{-}$ . The iodine is titrated with sodium thiosulphate, $I X_{2} + 2 S X_{2} O X_{3} X^{2 -} 2 I X^{-} + S X_{4} O X_{6} X^{2 -}$ . How many moles of $Na X_{2} S X_{2} O X_{3}$ are consumed per mole of $O X_{3}$ ?

One mole of

O X_{3}

liberates one mole of

I X_{2}

, and each mole of

I X_{2}

reacts with 2 mol of

S X_{2} O X_{3} X^{2 -}

. So 2 mol of thiosulphate correspond to 1 mol of ozone.