A mixture of dihydrogen and dioxygen at one bar pressure contains 20% by weight of dihydrogen . What would be the partial pressure of dihydrogen in bar ?

Options

A. `0.8`
B. `1.8`
C. `2.8`
D. 3

Answer

A

Explanation

Let the total mass of the mixture be 100 g
Mass of `H_(2)=(20)/(2)=10` moles
Mass of `O_(2)=100-20=80 g`
No. of moles of `O_(2)=(80)/(32)=2.5` moles
Total number of moles of `H_(2)` and `O_(2)=10+2.5=12.5`
Mole fraction of `H_(2)=(10)/(12.5)=0.8`
Total pressure of mixture = 1 bar
`therefore` Partial pressure of `H_(2)` in the mixture, `p_(H_(2))`
= Mole fraction `xx` Total pressure `=0.8xx1=0.8` bar