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Topic: Autoionization of water  (Read 4772 times)

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Offline gear2d

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Autoionization of water
« on: August 17, 2008, 12:20:20 AM »
2H2O  :rarrow: H3O+ + OH-  (At equilibrium)

A) I was wondering why does increasing the temperature causes [H+] to increase and nothing happens to [OH-]?

B) Why does the equilibrium lies a far to the left?

Offline Astrokel

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Re: Autoionization of water
« Reply #1 on: August 17, 2008, 12:49:57 AM »
Hey!

1) Perhaps [H+] = [OH-] at equilibrium after increasing the temperature, i don't see why only [H+] increases.

2) What do you know about the enthalpy change of autoionization of water?
No matters what results are waiting for us, it's nothing but the DESTINY!!!!!!!!!!!!

Offline sameeralord

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Re: Autoionization of water
« Reply #2 on: August 17, 2008, 09:16:25 AM »
2H2O  right arrow H3O+ + OH-

Is an endothermic reaction. If you increase the temperature energy is added to the system according to Le chatelier the system would partially oppose the change by removing the excess. Hence going in the endothermic direction (net forward)

equilibrium lies to the right not left

This would increase the concentration of H30+ and OH- by same amounts.

The PH would fall because there is more H30+

The solution is still neutral though because eventhough the PH falls there is also a new water constant. It is no longer 10^-14. At this new constant this PH is considered neutral.

Obviously the concentration H3O+ = OH- also. Further proof it is neutral.
Hope this helps  ;)

Offline Astrokel

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Re: Autoionization of water
« Reply #3 on: August 17, 2008, 09:24:56 AM »
hey!!

Quote
equilibrium lies to the right not left

I guess question B is not related to A, because if so the equilibrium will lie to the right as you had said!
No matters what results are waiting for us, it's nothing but the DESTINY!!!!!!!!!!!!

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