A solution of 10g of a nonvolatile compound in 25g of water boils at 100.78C at 1 atm. What is the molecular mass of the solute?

1 answer

The normal boiling point of water is 100.00 C. This boils at 100.78; therefore, delta T = 100.78-100.00 = ?
Then delta T = Kb*molality. Substitute and solve for m = molality.

m = mols/kg solvent. You have kg solvent and m, solve for mols.

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