Question

Which of the following solutions would have the highest osmotic pressure?
0.15 M KCl
0.2 M C6H12O6
0.2 M C12H22O11
0.2 M CH3COOH
0.15 M CaCl2

Answer 1

pi = i*M*RT.
i = van't Hoff factor.
i = 2 for KCl
i = 1 for C6H12O6
i = 1 for C12H22O11
i = 1 for CH3COOH
i = 3 for CaCl2

Note that you don't need to actually calculate pi to do this; i.e., R and T are constants; all you need are i and M. i*M is the determining factor.