Osmotic pressure and molecular weight??

Question

A solution is prepared by dissolving 6.00 g of an unknown nonelectrolyte in enough water to make 1.00 L of solution. The osmotic pressure of this solution is 0.750 atm at 25.0C. What is the molecular weight (g/mol) of the unknown solute?

Answer 1

osmotic pressure = C RT

0.750 = C x 0.0821 x 298 K

C = 0.0307 = moles solute / Volume solution = moles solute / 1.00 L

moles solute = 0.0307

Molar mass = 6.00 / 0.0307 = 195.4 g/mol