Question

Hey guys I was wondering if you guys know the answer to this:

Which of the following is NOT true of colligative properties? Colligative properties are...

A. independent of the chemical identity of the solute.

B. responsible for lowering the vapor pressure of a solution versus the vapor pressure of the pure solvent.

C. dependent on the molar mass of the solute.

D. dependent on the mass of solute present.

E. all of these are true.

I am thinking it is D?

Answer 1

I believe you need to rethink this question. For example, in the freezing point depression, we have
delta T = Kf* molality
and molality = moles solute/kg solvent
and moles solute = grams/molar mass.

So I would think adding grams makes more moles and more moles increases molality and more molality increases delta T. So it looks to me that it IS dependent upon the mass of the solute.

Answer 2

The answer is C. I had got it wrong, but I looked at the posted correct answers and it says the not true statement is(not sure why):

dependent on the molar mass of the solute.