P°(hexane) = 408 Torr, P°(heptane) = 141 Torr. x(hexane) = 0.300. Find Y₆ and Y₇.

Step-1: Partial pressures:

P(hexane) = 0.300 × 408 = 122.4 Torr

P(heptane) = 0.700 × 141 = 98.7 Torr

Step-2: Total pressure:

P_total = 122.4 + 98.7 = 221.1 Torr

Step-3: Vapour mole fractions:

Y₆ (hexane) = 122.4 / 221.1 ≈ 0.554

Y₇ (heptane) = 98.7 / 221.1 ≈ 0.446

Answer: Y₆ ≈ 0.554, Y₇ ≈ 0.446