Henderson-Hasselbach Equation

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Sebastian Hurtado 1J
Posts: 42
Joined: Fri Sep 25, 2015 3:00 am

Henderson-Hasselbach Equation

Postby Sebastian Hurtado 1J » Thu Dec 03, 2015 9:13 pm

Could someone please explain the derivation of the Henderson-Hasselbach equation and what exactly it represents? When would you use it and how would you know when to use it?

Jonathan Shih 3H
Posts: 37
Joined: Fri Sep 25, 2015 3:00 am

Re: Henderson-Hasselbach Equation

Postby Jonathan Shih 3H » Fri Dec 04, 2015 7:23 am

I don't the knowing the derivation of the equation is very important, but it is very important that you know when to use it. In most acid-base reactions, we would typically just calculate what we need using ICE boxes. However, to get the pH of buffer solutions, we use the Henderson Hasselbach (if you're confused what a buffer solution is, refer back to the course reader notes).

Now that you know to use it for buffer solutions, to actually use it, simply plug in the components of the equation in order to get the pH.


Also, if you're actually just curious about the derivation of the equation, I hope this link helps clarify where this very useful equation came from:http://pharmaxchange.info/press/2012/10/henderson%E2%80%93hasselbalch-equation-derivation-of-pka-and-pkb/

I hope this helps!

Sebastian Hurtado 1J
Posts: 42
Joined: Fri Sep 25, 2015 3:00 am

Re: Henderson-Hasselbach Equation

Postby Sebastian Hurtado 1J » Fri Dec 04, 2015 9:28 am

Thank you! This did in fact help a lot! However, I'm still a bit confused on how you would know whether you are dealing with a typical acid-base reaction requiring the use of ICE boxes or if you are dealing with buffer solutions. Any clarification would be greatly appreciated. Thank you again!

Jonathan Shih 3H
Posts: 37
Joined: Fri Sep 25, 2015 3:00 am

Re: Henderson-Hasselbach Equation

Postby Jonathan Shih 3H » Fri Dec 04, 2015 4:10 pm

I'm glad it did!

To explain further:
You know when it's a buffer when it's a weak acid and it's conjugate base or when it's a weak base and it's conjugate acid. I thinkt here's more clarification on page 156 of the course reader, where it's explained what a buffer is and actually uses the Henderson Hasselbach equation at the bottom (well, a case of it when the concentrations of the acid and its conjugate base are equal).


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