Question

20 ml of mixture of O2 and O3 was heated till ozone was completely decomposed. The mixture on cooling was found to have volume 21 ml. Calculate % of ozone by volume in mixture

Answer 1

let the volume of ozone in the mixture is x ml , therefore volume of oxygen in the mixture is 20 - x ml 
now decomposition of ozone can be represented by  2O3 ---> 3O2
3 x 22400 ml of O2  is formed from 2 x 22400 ml 0f O3
 therefore x ml of O3 will give 2/3 x ml of O2 , now 
 x + (20 - x) + 2/3x = 21 , on solving we get 
x = 3/2ml = 1.5 ml 
therefore % age of ozone in the mix = 1.5 / 20   x  100 = 7.5% by volume