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2) A 1.00 m solution of acetic acid (CH3COOH) in benzene has a freezing point depression of 2.6 K. Calculate the value for i and suggest an explanation for its value.
What about i = 0.5?
Think of it in the reverse fashion to i = 2 and one item (like a molecule) into solution yielded two items (the dissociated molecule) in solution. This is the reverse. When one item goes into solution, only one-half is present in the solution. Sort of a reverse dissociation - call it an association.
Maybe if I went to whole numbers? If two solute items go into solution, only one item is present in the solvated state.
The acetic acid dimerized in the benzene and formed (CH3COOH)2. Two molecules went it, but only one item (the dimer) is present in solution.
Think how confused poor J.H. van't Hoff must have been. And then, when he got to the right answer, I think the joy of figuring it out must have been mixed with some relief.