Finding OH concentration

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Samuel G Rivera - Discussion 4I
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Finding OH concentration

Postby Samuel G Rivera - Discussion 4I » Fri Jan 24, 2020 1:17 am

I'm confused on how to find [OH-] from only knowing [H30+]. In problem 6B.9, when [H3O+] is 1.5M, the answer for [OH-] is supposed to be 1.5 x 10^-14 but I keep getting 6.67 x 10^-15. What I'm doing is taking Kw = [H3O+][OH-] and then dividing [H3O+] on each side but it gets me the wrong answer.

Eugene Chung 3F
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Joined: Wed Nov 15, 2017 3:03 am

Re: Finding OH concentration

Postby Eugene Chung 3F » Fri Jan 24, 2020 3:26 am

I'm pretty sure the solution is wrong (I have the same problem). Since [H30][OH]=1*10^-14, the answer would not be what it says in the solutions.

Ariel Davydov 1C
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Re: Finding OH concentration

Postby Ariel Davydov 1C » Fri Jan 24, 2020 10:04 am

What the solutions manual is doing is converting the [OH-] concentration to pOH, finding pH by subtracting pOH from 14, and then calculating [H3O+] by using the pH value. This method will result in a different result if the concentration of H3O+ or OH- exceeds 1 M.


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