posted by Robby on .
Calculate the molecular weight of a small protein if a 0.32 g sample dissolved in 161 mL of H2O has an osmotic pressure of 9.0 mmHg at 25 degree celcius. (R=0.0821 L X atm/K X mol)
pi = MRT
Substitute and solve for M = molarity.
Then M = mols/L. Substitute 0.161 for L and solve for mols.
Then mols = n = grams/molar mass.
You know n and grams, solve for molar mass. By the way, pi must be in atm. pi = 9.0 mm/760 = ?