Heptane and octane form ideal solution. At `373K`, the vapour pressure of the two liquids are `105.2 kPa` and `46.8 kPa` respectively. What will be the vapour pressure, in bar, of a mixture of `25g` of heptane and `35g` of octane?

Explanation

(A) Heptane `C_(7)H_(16) m_(A)=100`
(B) Octane `C_(8)H_(18)m_(B)=114`
`n_(A)=(w_(A))/(m_(A))=(25)/(100)=0.25,n_(B)=(35)/(114)=0.3`
`x_(A)=(0.25)/(0.25+0.30),x_(B)=(0.3)/(0.25+0.30)`
`=0.45 " "=0.55`
`p=p_(A)^(0)x_(A)+p_(B)^(0)x_(B)`
`=105.2xx0.45+46.8xx0.55`
`=47.34+25.74=73.08kPa`.