When 0.855 g of this solid was dissolved in 7.50 g of napthalene, the solution had a freezing point of 78.0° C. The pure solvent freezes at 80.0° C; its molal freezing point constant is 6.8° C/m. What is the molecular formula of the compound?

Question

When 0.855 g of this solid was dissolved in 7.50 g of napthalene, the solution had a freezing point of 78.0° C.  The pure solvent freezes at 80.0° C; its molal freezing point constant is 6.8° C/m.  What is the molecular formula of the compound?

DrBob222 · Answer

delta T = Kf*molality Solve for molality molality = moles/kg solvent Solve for moles. moles = grams/molar mass Solve for molar mass.