UPSEE Solved Model Paper 1

For an ideal solution, obeying Raoult’s law, the vapor pressure of mixture.
=

p°

methanol

‌

x°

methanol

+

p°

ethane

‌

x°

ethanol

Pmixture = 88.5 ×

16∕32

16 32 + 46 46

+ 42.0 ×

46∕46

16 32 + 46 46

Pmixture = 88.5×

0.5

1.5

+42.0 ×

1

1.5

= 57.44 mm
The mole fraction of any constituent 'i' in vapor phase is =

xipi*

ptotal

For methanol, mole fraction = 88.5×

[ 16 32 16∕32+46∕46 ]

57.44

Or the mole fraction of methanol in vapor phase = 29.47/57.44 = 0.5130