Calculate the mole fraction of benzene in a mixture that contains 45.2 g of benzene and 115.8 g of toluene.

molecular weight of toluene = 92 g/mol

C6 = 12 x 6 = 72

H5 = 1 x 5 = 5

CH3 = 12 + 1 x 3 = 15

molecular weight of benzene = 78 g/mol

C6 = 12 x 6 = 72

H6 = 1 x 6 = 6

moles toluene:

115.8 / (92 g/mol) = 1.25 mol

moles benzene:

45.2 / (78 g/mol) = 0.57mol

total moles: 1.25 + 0.57 = 1.82 moles

mole fraction of toluene:

1.25 mol / 1.82 moles = 0.68