Benzene and naphthalene form ideal solution over the entire range of composition. The vapour pressure of pure benzene and naphthalene at 300 K are 50.71 mm Hg and 32.06 mm Hg respectively. Calculate the mole fraction of benzene in vapour phase if 80 g of benzene is mixed with 100 g of naphthalene.

Question

Philoid · Accepted Answer

Given-

of benzene = 50.71 mm Hg

of naphthalene = 32.06 mm Hg

Using the formula of lowering vapour pressure to calculate mole fraction of benzene and naphthalene in solution,

Thus,

Using formula for vapour pressure,

Mole fraction of benzene in vapour phase is calculated by,

Thus, mole fraction of benzene in vapour phase is 0.6744