Question

If the same solute is dissolved in two different solvents to the same concentration and the same temperature, the osmotic pressure ____
will be the same for both.
will be different.
may be the same or different, depending on the solute.
will be lower in the solvent with higher molecular weight.

I don't understand how the colligative properties will vary by solvent through the equation pi=iMRT. Isn't the molarity calculated through moles of solute/ "L of solvent"? However, in reality, this is physically impossible. I think it is the fourth choice, simply because higher molecular weight will cause lower moles of solvent.

Answer 1

If i, M, R, and T are the same, how can pi be any different? However, the problem doesn't state that i is the same; only that the two solvents are different. So how pi varies will depend upon how the solute and solvent interact (how i changes) and that isn't one of the choices. I would pick "none of the above" if given the choice.