Question

The freezing point of an aqueous solution of glucose was measured to be -1.52 oC. What is the osmotic pressure, in atm, of 100 mL of this solution at 25.0 oC? (Kf = 1.86 oC/m)

When I calculated it out I got 16.79 atm but the answer was wrong don't know what I messed up on.

Answer 1

If I use 1.52 = Kf*m I get something like 0.817 m for the concn of the glucose. If we assume molality is molarity (and with no density listed that's the best we can do), then pi = MRT = 0.817 x 0.08206 x 298 = 19.98 atm. Check my work.