Finding the lowest freezing point....?

[drzakisadiq]

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On destoyer problem 18, I understand that freezing point depression is a colligative property, so it will depend on the van Hoft factor, the number of molecules it separates into.

But my question is, what if the I were asked, which had the highest freezing point, would I then look for the one that has the lowest i factor?

And what about for boiling point elevation. I'm guessing if they were to ask me which had the highest boiling point, I would look for the one with the greatest i factor once again? Correct me if I'm wrong. Thanks

 

[alanan84]

Yeah I was just going to post a question having to do with this destroyer problem. My guess in response to your question is that your assumptions are correct. Destroyer says that compounds with the highest vant hoff factor with have the lowest freezing point, lowest vapor pressure, highest osmotic pressure, and highest boiling point so I imagine the opposite is also true. Someone correct me if I'm wrong.

Real quickly, does Na2SO4 dissociate into 3 particles because there are 2 Na?

 

[Dental4ever]

it depends on the molarity too . for example, 2M of NaCl and 1M of Na2SO4. even the i for Na2SO4 is 3 and i for NaCl is 2, 3x1 <2x2

 

[alanan84]

it depends on the molarity too . for example, 2M of NaCl and 1M of Na2SO4. even the i for Na2SO4 is 3 and i for NaCl is 2, 3x1 <2x2

Isn't it molality?

 

[flampard]

as boiling point increase the vapor pressure decreseas. since both of these guys are colligative properties increaseing the i will infact increase both of the numbers but do different things though! Vapor pressure and the freezing point will get substracted for the original numbers but the boiling point will get added up to the orinal.

 

[Dental4ever]

ops..yes it's the molality. Tf= Kf(m)

 

[atlanta213]

Molarity X number of ion dissociated in water

 

[yakuza]

yehhh so the more something dissociations, the stronger:

Freezing point depression
Boiling point elevation
Vapor pressure depression

 

[atlanta213]

yehhh so the more something dissociations, the stronger:

Freezing point depression
Boiling point elevation
Vapor pressure depression

Good job!🙂

I will add one more thing along with boiling point. Osmotic pressure elevate as well.