## Applying Kw

KDang_1D
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### Applying Kw

In lecture, Dr. Lavelle did an example using Ba(OH)2 to show that Kw, a special value of Ka, can be used to determine [H3O+]. Why is this possible? Don't all aqueous reactions have different Ka values, so shouldn't Ba2+ affect the value of Ka/Kw?

sbeall_1C
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Joined: Sat Sep 07, 2019 12:17 am
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### Re: Applying Kw

Ba2+ is the cation of a strong base, so when it dissociates it will not affect the pH of the solution. Kw refers to the equilibrium constant for water, and shows how water has a neutral pH of 7. So the OH will increase the pH which changes the Kb and therefore allows us to calculate the Ka using Kw=(Ka)(Kb)=1.0x10^-14.

Jared_Yuge
Posts: 100
Joined: Sat Aug 17, 2019 12:17 am

### Re: Applying Kw

Kw is really nifty because if you have one of [OH-] or [H30+] you can find the other because you know Kw is 10^-14. Ba(OH)2 adds to the [OH] (you know Ba2+ doesnt affect) then you use the new [OH-] to find the [H30+].