For estimating ozone in the air, a certain volume of air is passed through an . Alkaline Kl solution when `O_(2) ` is evolved and iodide is oxidized to iodine . When such a solution is acidified , free iodine is evolved which can be titrated with standard `Na_(2)S_(2)O_(3)` . Solution : in an experiment, 10 L ari at 1 atm and `27^(@) C` were passed through an alkaline Kl solution , and at the end, the iodine was entrapped in a solution which on titration as above required `1.5` ml of `0.01 N Na_(2)S_(2)O_(3)` solution. Calculate volume percentage of ozone in the sample.

Explanation

The chemical reaction is , `H_(2)O + Kl + O_(3) to l_(2) + O_(2) + KOH `
Milliequivalents of iodine = Milliequivalents of Kl = Milli equivalents of `O_(3)` reacted
Milliequivalnets of `Na_(2)S_(2)O_(3) = 1.5 xx 0.01 = 1.5 xx 10^(-2)`
Millimoles of iodine ` = (1.5 xx 10^(-2))/2 = 7.5 xx 10^(-3) " " [ :. " n-factor for iodine " =2]`
Millimoles of ozone ` = 7.5 xx 10^(-3)`
Volume of ozone ` = (nRT)/P = (7.5 xx 10^(-6) xx 0.0821 xx 300)/1 = 184.725 xx 10^(-6) ` litre
Volume per cent of ozone ` = (184 .725 xx 10^(-6))/10 xx 100 = 1.847 xx 10^(-3)`