A 1.60 g sample of a mixture of naphthalene, C10H8, and anthracene, C14H10, is dissolved in 20.0 g benzene, C6H6. The freezing point of the solution is 2.81oC. What is the composition as mass percent of the sample mixture?

Answer 1

% w/w = (mass solute/total mass solution)*100 = ?
mass solute = 1.60 grams.
mass solution = 20.0 + 1.60 = 21.60 grams.

Substitute and solve.

Answer 2

7.4%