Colligative Properties

[aclementine]

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Which of the following is NOT a colligative property?
a) freezing point depression
b) osmotic pressure
c) melting point depression
d) boiling point elevation
e) vapor pressure lowering

 

[PiBond]

I think they're all colligative properties...unless my Bud Light is making my brain sluggish...

 

[aclementine]

ok, that's what I thought too, but the answer is "c) melting point depression"... this can't be right can it? I thought freezing point depression was the same as melting point depression, right?

 

[PiBond]

that is correct

 

[loveoforganic]

ditto on all colligative

 

[aclementine]

Phew, it's not just me then. Thanks for the confirmation guys 🙂

I posted this question in the DAT forums as well, and it seems like they have a different point of view though: http://forums.studentdoctor.net/showthread.php?t=674995

 

[loveoforganic]

Just read the dat thread and did a little research. Agree with the guy in that thread. I was familiar with the reduced melting point of nanoparticles, but didn't know it was termed. Melting point depression I just assumed to be a synonym for freezing point depression.

 

[chemtopper]

Freezing point is not a characteristic property of a substance.
Melting point is a characteristic property of the substance and it depends on the size of the particle also.Check the meaning of melting point depression from the link given below.This will help you in understanding it well.


http://en.wikipedia.org/wiki/Melting-point_depression

 

[aclementine]

Wow, this is so key. Just to confirm:

Melting point depression --> usually seen in nanoparticles --> Particle properties (not quantity) matter --> NOT colligative property

Is this thinking right?

 

[loveoforganic]

Looks right to me.

 

[kidkay]

Which of the following is NOT a colligative property?
a) freezing point depression
b) osmotic pressure
c) melting point depression
d) boiling point elevation
e) vapor pressure lowering

Its 'c'.

 

[kentavr]

What was the source of your question?
Question looks rather strange to me, given the answers above. Temperature is the macro scale thermodynamic parameter, it needs additional (not in MCAT) assumptions to extend this concept to nano scale. I would say that at nano scale average energy of particles(Temperature) should expect some quantum effects. In sum, I would suspect that the question is not correct.

 

[rama kandra]

This was news to me, but I think it makes sense now. I doubt the MCAT would test it, but I am preparing for anything.