A molecular compound has the empirical formula CH2. When 100mg of the compound is dissolved in 1.00 g of benzene, the solution freezes 1.75 degrees celsius lower than pure benzene. The Kf for benzene is 4.90 C/m. What is the MM of the compound?

Answer 1

delta T = Kf*m
Substitute and solve for m

m = mols solute/kg solvent
Substitute and solve for mol solute.

mols = grams/molar mass. You know grams and mols, solve for molar mass.

Then (empirical molar mass)*x = approx molar mass.
Solve for x and round to whole number.