Question

Ethylene dibromide and 1,2 dibromopropane form a series of ideal solution over the whole range of composition. At 85°C the vapour pressure of two liquids are 173Tand 127T respectively. What should be the mole fraction of ethylene dibromide in solution at 85°C if both are present with 1:1 molar mixture in the vapour

Answer 1

Answer:

Mole fraction of ethylene dibromide = 0.5

Explanation:

Ethylene dibromide   &    1,2- dibromopropane

Pa = 173 torr                                Pb = 127 torr

As per Raoult's law :

x mole / liter

Ps = Pa xa

Ps = 173 x  x / x + x

Ps = 173 x 1 / 2

Ps = 86.5

Again applying Raoult's law:

Ps = Pa xa

xa = Ps / Pa

xa = 86.5 / 173

xa = 0.5

Mole fraction of ethylene dibromide = 0.5