An ideal solution was obtained by mixing methanol and ethanol. If the partial vapour pressure of methanol and ethanol are 2.619 kPa and 4.556 kPa respectively, the composition of vapour (in terms of mole fraction) will be

Options

A. 0.635 MeOH, 0.365 EtOH
B. 0.173 MeOH, 0.827 EtOH
C. 0.574 MeOH, 0.326 EtOH
D. 0.365 McOH, 0.635 EtOH

Answer

D

Explanation

`P_("Total") = 2.619 + 4.556 = 7.175 kPa`
Mole fraction in vapour phase `= ("Partial pressure")/("Total pressure")`
`X_(MeOH)=(2.619)/(7.175) = 0.365 implies X_(EtOH) = 1 -0.365 = 0.635`