A mixture of `O_(2) and H_(2)` gases contains 20% of `H_(2)` gas. At a certain temperature, the total pressure of the mixture is found to be 1 bar. What is the partial pressure of `O_(2)` (in bar) in the mixture?

Explanation

In the mixture, 20% `H_(2)` is present. Hence extent of oxygen=80%.
`therefore n_(H_(2))=(20)/(2)=10 and n_(O_(2))=(80)/(21)=(5)/(2)`
`therefore`Total number of moles`=(10+(5)/(2))=(25)/(2)`
`therefore p_(O_(2))=(5)/(2)xx(2)/(25)xx1` bar `=0.2` bar.