Acids & Bases: Calculating the pH

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Sean Phen
Posts: 121
Joined: Wed Sep 30, 2020 10:01 pm

Acids & Bases: Calculating the pH

Postby Sean Phen » Sun Feb 21, 2021 10:16 pm

How do you calculate the Kb of a solution if you already know the Ka value? I know that I have to subtract the Ka value by 14, but sometimes it comes out wrong. I am confused on why that is.
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Sydney Lam_2I
Posts: 106
Joined: Wed Sep 30, 2020 10:09 pm

Re: Acids & Bases: Calculating the pH

Postby Sydney Lam_2I » Sun Feb 21, 2021 10:26 pm

Hi! So actually the formula for Ka and Kb is Ka*Kb=1.0*10^-14. I believe you're mixing up when pKa+pKb=14!
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Aaron Akhavan-Dis1B
Posts: 106
Joined: Wed Sep 30, 2020 9:59 pm

Re: Acids & Bases: Calculating the pH

Postby Aaron Akhavan-Dis1B » Sun Feb 21, 2021 10:29 pm

Ka x Kb = Kw. Kw is 1.0x10^-14. You're thinking of pKa and pKb, thats where you subtract 14. to find either value.
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