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Author Topic: How does temperature affect the amount of oxygen dissolved in water?  (Read 16363 times)

Offline elegantlywasted

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Hey guys its been a while, my roommate has a question for you all:

How does temperature effect the amount of dissolved oxygen in water?!?
« Last Edit: 09/10/2007 08:52:54 by chris »


 

Offline Soul Surfer

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In general liquids dissolve less gas as the temperature rises
 

Offline rosy

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Gases are more soluble in cold solutions than in hot ones.

For those who are interested in that sort of thing, this is because the favourable interaction enthalpy (van der Waals etc) is more important at lower temperatures but the entropy gain on going from a liquid to a gas is more important at higher temperatures.
If anyone who knows what I'm talking about wants to express that in layman's terms that would be good, I can't think how to at the moment..
 

Offline lightarrow

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Gases are more soluble in cold solutions than in hot ones.

For those who are interested in that sort of thing, this is because the favourable interaction enthalpy (van der Waals etc) is more important at lower temperatures but the entropy gain on going from a liquid to a gas is more important at higher temperatures.
If anyone who knows what I'm talking about wants to express that in layman's terms that would be good, I can't think how to at the moment..
ΔG = ΔH - TΔS   :)

In more layman terms: gas particles want to be as "free" as they can, occupying as much space as they can, because they are "independent" and the greater the temperature, the greater their speed; at low temperature, their speed is low, so they can "attach" to the solvent molecules (there is a sort of "glue" between them); when the temperature rises, the gas molecules become more "agitated" and the glue can no longer take them inside the solvent.

In the previous formula, you can see ΔG as a measure of the solvent's ability to keep the gas molecules inside; ΔH as a measure of the "glue strenght" and ΔS as a measure of the gas molecules "will" to escape; clearly T is the temperature. As you see, the more the "glue strenght" ΔH and the more the solvent can keep the gas; on the other hand, the more the gas molecules "will" to escape, the less the solvent can keep it; the same with temperature: the more T, the less is ΔG.
 

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