The vapour pressure of hexane `(C_(6)H_(14))` and heptane `(C_(7)H_(16))` at `50^@C` are 408 torr and 141 torr, respectively. The composition of the vapour above a binary solution composition a mole fraction of `0.300` hexane is `(y_(6)=` mol fraction of hexane and `y_(7) =` mol fraction of heptane)

Options

A. `Y_(6)=0.8,Y_(7)=0.2`
B. `Y_(6)=0.554,Y_(7)=0.446`
C. `Y_(6)=0.300,Y_(7)=0.700`
D. `Y_(6)=0.871,Y_(7)=0.129`

Answer

B

Explanation

`Y_(6)=(P_(6)^(@)X_(6))/(P)=(408xx0.3)/(P)…(1)`
`Y_(7)=(P_(7)^(@)xxX_(7))/(P)=(141xx0.7)/(P)…(2)`
Dividing equation (1)by(2), we get
`(Y_(6))/(Y_(7))=1.24 &Y_(6)+Y_(7)=1`
`:. Y_(7)=0.446&Y_(6)=0.554`