Biphenyl, c12h10,c12h10, is a nonvolatile, nonionizing solute that is soluble in benzene, c6h6.c6h6. at 25 ∘c,25 ∘c, the vapor pressure of pure benzene is 100.84 torr. what is the vapor pressure of a solution made from dissolving 19.2 g19.2 g of biphenyl in 33.7 g33.7 g of benzene?

Vapour pressure of solution is 78.151 torr

Explanation:

Molar mass of biphenyl = 154.21 g

Molar mass of benzene = 78.11 g

19.2 g biphenyl = (19.2/154.21) moles of biphenyl = 0.125 moles of biphenyl

33.7 g of benzene = (33.7/78.11) moles of benzene = 0.431 moles of benzene

Total number of moles = (0.125+0.431) moles = 0.556 moles

Mole fraction of benzene in solution = (0.431/0.556) = 0.775

According to Roults law, vapour pressure of solution made from non-volatile solute =

Here solute is biphenyl and solvent is benzene

So, vapour pressure of solution = = 78.151 torr