Dilution of the solvent adds new energy states to the liquid, but does not affect the solid phase.

The above line appeared on the following page under the section "5: Colligative properties and entropy" and the last paragraph

Actually, I can understand a little bit. According to me, while freezing the solvent freezes separately from the solute( ie If we freeze salt and water solution, the salt will be separated out from ice). Therefore, whatever the presence of the solute maybe, the solid form of solution consists of solid 'ice', which is identical in every case and hence have identical entropy.

Am I going right? Is there an alternative explanation?

I am not clear with the concepts of what actually happens when we freeze a solution. Any Links regarding it or any other related stuff will be welcomed.


1 Answer 1


Instead of "making the jump" from liquid to gas, the water molecules are trying to stack together into an ice crystal. The salt molecules again get in the way. Think of making a solid as like stacking shoeboxes, but the shoeboxes are vibrating slightly. The higher the temperature, the more they vibrate. At some temperature (the melting point), the vibration gets so powerful that the whole shoebox stack collapses. Now imagine that instead of a stack of just shoeboxes (pure ice), you start putting golf balls in between some of the shoeboxes. Those are salt molecules. They get in the way of the ordered stack, they mess everything up, they make the stack collapse really easily. There has to be a lot less vibration (lower temperature) to stack the boxes when there are golf balls getting up in everyone's business. So the freezing point is reduced.

  • $\begingroup$ Quite a nice analogy. :) But it doesn't answer my question. :/ $\endgroup$
    – sedflix
    May 2, 2015 at 5:14
  • $\begingroup$ @SiddharthYadav do you want a thermodynamic explanation for the colligative property ? I can give a free energy explanation. Do you want to know why dilution doesnt affect solid phase or something else ? $\endgroup$
    – Gowtham
    May 2, 2015 at 5:48
  • $\begingroup$ I want to know 'why dilution doesn't affect solid phase'... $\endgroup$
    – sedflix
    May 2, 2015 at 14:23

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