Oh

Tempestuousfury

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Learning about colligative properties and solutions and whatnot in AP Chemistry, and I found an answer to a question posed by many newbies (or, rather, questions to stock suggestions when tropical and coldwater fish are mixed).

Citation:
Chemistry & Chemical Reactivity: Fourth Edition Kotz, John C. Saunders College Publishing, New York: 1999.

Not the best of citations, but most of the info is there.

Now, this is a direct quote, no paraphrasing, and I have done nothing but copy this passage from the textbook.

"The solubility of all gases in water decreases with increasing temperature. You may realize this from everyday observations such as the appearance of bubbles of gas that are seen as water is heated mildly (below the boiling point), and from the fact that gas evolution is less vigorour from a bottle of a carbonated beverage when it is cold than when it is warm.

"Decreased solubility of gases with increasing temperature has environmental consequences. Fish often seek lower temperatures in summer because the warmer surface layers of water have lower oxygen concentrations. Thermal pollution, resulting from the use of surface water as a coolant for various industries, can be a special problem for marine life that requires oxygen to survive. Effluent water returned to a natural water source at a warmer temperature will be depleted of oxygen."

And there you have it.
 
wow, i've sometimes wondered about that :nod:

maybe we should pin this to let newbies know why for once and for all

thanx for that

DD
 
What I've never understood is that heating water increases the solubility and saturation point of solids, (think sugar in tea) but decreases the solubility & saturation levels of gases.

So why is that?
 
The higher temps = more solubility is not always true, but very often is. Some compounds that are less soluble at high temps (barely any difference in solubility with greater temps) are Li2SO4 and salt (NaCl) goes down and up...

The book states there is no given pattern...


Ah, now I know, sort of. Well, it says that since nature favors entropy, when gases are dissolved by the solvent, energy is given off (exothermic), therefore, the system loses energy and gains entropy.

Now, if the system is at a higher temperature, the intermolecular bonds break, adding energy to the system and allowing the gas molecules to leave the solvent.

Well, I think that is all that I can offer, seeing as how that is pretty much all that is in that section...
 

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