Ozone an estimated in air by passing certaing volume of air through an acidified or neutral or basic KI solution when O_(2) is evolved and I^(ɵ) is oxidised to I_(2). Free I_(2) evolved is titrated with standard Na_(2)S_(2)O_(3) solution. In an experiment 10 L of air at 1 atom and 27^@C was passed through an alkaline KI solution and I_(2) liberated requried 2 " mL of " (M)/(800)Na_(2)S_(2)O_(3) solution. Calculate the volume percentage of O_(3) in sample.

Ozone an estimated in air by passing certaing volume of air through an

1.	Ozone an estimated in air by passing certaing volume of air through an acidified or neutral or basic KI solution when O_(2) is evolved and I^(ɵ) is oxidised to I_(2). Free I_(2) evolved is titrated with standard Na_(2)S_(2)O_(3) solution. In an experiment 10 L of air at 1 atom and 27^@C was passed through an alkaline KI solution and I_(2) liberated requried 2 " mL of " (M)/(800)Na_(2)S_(2)O_(3) solution. Calculate the volume percentage of O_(3) in sample.
Answer» Solution :Write the balanced REDOX REACTIONS in basic medium. `2I^(ɵ)+H_(2)O+O_(3)toO_(2)+I_(2)+2overset(ɵ)(O)H` (n factor `O_(3)=2`) `I_(2)+2e^(-)to2I^(ɵ)(n=2)` `S_(2)O_(3)+10overset(ɵ)(O)Hto2SO_(4)^(2-)+5H_(2)O+8e^(-)(n=8)` `thereforem" Eq of "I_(2)=m" Eq of "Na_(2)S_(2)O_(3)` `=2xx(1)/(800)xx8` (n factor) `=0.02` mmol es of `I_(2)=(0.02)/(2)=mmol es of O_(3)` `[becausen=2` for both or molar ratio of `O_(3):I_(2)::1:1`] `P_(O_(3))=(nRT)/(V)` `=(0.01xx10^(-3)xx0.0821xx300)/(10)` `=246.3xx10^(-7)atm` Volume `% of O_(3)=246.3xx10^(-7)xx100` `=2.463xx10^(-3)%`