Using Ka Kb and Kw to find K

Acidity
Basicity
The Conjugate Seesaw

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JasmineAlberto4J
Posts: 73
Joined: Fri Sep 25, 2015 3:00 am

Using Ka Kb and Kw to find K

Postby JasmineAlberto4J » Wed Nov 25, 2015 12:44 am

I understand that Ka x Kb =Kw but what is the relationship between these three and K? how can you use these three to find K?

Richmund Tan 1L
Posts: 25
Joined: Fri Sep 25, 2015 3:00 am

Re: Using Ka Kb and Kw to find K

Postby Richmund Tan 1L » Wed Nov 25, 2015 1:40 am

Ka is the acid ionization constant, and Kb is the base ionization constant. They can be likened to either the Lewis or Bronsted-Lowry definitions of acid/base.
I assume that when you state "K", you are referring to "Keq/Kp".
There really is no Keq/Kp for acid/base questions. You're essentially calculating either the Ka or Kb, depending on the equation.
Kw is a constant. It is always 10^-14.
Think of Ka and Kb as inverses, but when they multiply, they equal Kw.
Also, taking the -log of Ka and Kb will get you pKa and pKb.
When they add, they equal 14. This makes sense because that is the maximum value on the pH scale.

Hope this helps!


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