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Topic: Will an insoluble material lower the freezing point of a solvent?  (Read 17359 times)

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Offline OrganicSynthesis

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Re: Will an insoluble material lower the freezing point of a solvent?
« Reply #15 on: January 19, 2010, 12:56:54 PM »
I think the answer is that it does have a very slight change on the freezing/boiling points just because of the intermolecular attractions of the insoluble substance.

BUT, I think it's only changed extremely slightly, because of observation. Let's say you have a pot of water, maybe the pot is made of aluminum. Let's say you have a beaker full of water. Wouldn't they both freeze and boil at the same temperature? However, can't you technically say that the glass and the aluminum are insoluble substances touching the water?

I hope I'm not wrong but this is just my thinking.

Offline Ligander

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Re: Will an insoluble material lower the freezing point of a solvent?
« Reply #16 on: January 19, 2010, 04:23:18 PM »
can anyone tell me how to phrase the reasons for the answers? like some people say that the answer is yes or the answer is no. i am supposed to answer this for homework and we haven't reached a consensus yet here.
You can think about the problem in such way.

 Entropic factor in other words is the influence of particles other than molecules of solvent, i.e. that have another size, shape, electric and magnetic properties etc. that prevent from molecules of solvent to form regular geometric structures of a solid crystal at low temperatures(by increasing disorder) when there is already no preventing enthalpic factor(i.e. motion of molecules itself does not prevent from solvent to form solid crystal structure).

 Now imagine yourself a glass ball of radius 1 cm that you put into a beaker with distilled water. It is obvious that it wouldn't prevent from molecules of water to form crystals in their usual way, excluding a very thin layer adjacent to glass. Now you break the ball into billions of billions of pieces with volume that equals the volume  of 10-20 molecules of water and disperse them uniformly in the water(it is not dissolution). These pieces also would prevent from adjacent layers of water to form regular hexagonal patterns at usual freezing point. But now the "adjacent volume of water" appears to be a considerable part of the system so you would have to slow down the motion of molecules a bit more to force your water to freeze.

 You can think also about a handful of fullerens or a bundle of nanotubes that were put to a beaker with water.

Offline billnotgatez

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Re: Will an insoluble material lower the freezing point of a solvent?
« Reply #17 on: January 19, 2010, 08:56:17 PM »
do boiling chips change the boiling point
are they soluble

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