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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: ramble on April 20, 2006, 11:14:21 PM

Title: Partition Coefficient & Temperature
Post by: ramble on April 20, 2006, 11:14:21 PM
Why does partition coefficient depend on temperature only?

At first I thought it should be related to the kinetic energy of the molecules. But then shaking would increase the kinetic energy of molecules too, but it would not affect the partition coefficient.

Besides, would a change in kinetic energy has any effect on the partition coefficient?

It seems that I get all wrong..
Title: Re: Partition Coefficient & Temperature
Post by: Equi on April 21, 2006, 08:26:46 AM
Why does partition coefficient depend on temperature only?

At first I thought it should be related to the kinetic energy of the molecules. But then shaking would increase the kinetic energy of molecules too, but it would not affect the partition coefficient.

Besides, would a change in kinetic energy has any effect on the partition coefficient?

It seems that I get all wrong..
Because the temperature increases the solubility in both phases differently. E.g. water/octanol and salts: The solubility in the aqueous phase increases much more with temperature, as the solubility in the hydrophobic phase does.

Btw. the kinetic energy of shaking the flask is like a fart in a tornado compared with heating up the whole solution. ;)
Title: Re: Partition Coefficient & Temperature
Post by: ramble on April 21, 2006, 10:18:57 AM
Thx~

Quote
The solubility in the aqueous phase increases much more with temperature, as the solubility in the hydrophobic phase does.

Is it because strength of H-bond decreases in a much higher rate then that of normal van der Waals' forces when temperature is increased? If so, what is the cause of it?

Besides, is the decrease in inter-molecular forces caused by the increase in kinetic energy of the particles?
Title: Re: Partition Coefficient & Temperature
Post by: Equi on April 21, 2006, 04:24:29 PM
Thx~

Quote
The solubility in the aqueous phase increases much more with temperature, as the solubility in the hydrophobic phase does.

Is it because strength of H-bond decreases in a much higher rate then that of normal van der Waals' forces when temperature is increased? If so, what is the cause of it?
Carefully, this applies only to the salt example.

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Besides, is the decrease in inter-molecular forces caused by the increase in kinetic energy of the particles?
Puh, to be honest - I don't know.