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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: MR on March 20, 2017, 05:46:42 AM

Title: Buffer from non-conjugated acid/base
Post by: MR on March 20, 2017, 05:46:42 AM

Hi everyone,

If i want to make a buffer of potassium sorbate and malic acid which pka should i use to calculate the amount to use of each and how at pH 6.5?

Title: Re: Buffer from non-conjugated acid/base
Post by: Borek on March 20, 2017, 07:58:48 AM

This is tricky and not easy to calculate. First of all - you can't calculate the pH using just one pKa, you need all of them, especially when they are close.

Best approach is to use either some kind of universal solver to find out the solution to the equilibrium system, or specialized software like the Buffer Maker (http://www.chembuddy.com/?left=Buffer-Maker&right=buffer-calculator).

Title: Re: Buffer from non-conjugated acid/base
Post by: MR on March 20, 2017, 11:03:36 AM

Okay, I tried to use Buffer Maker for calculation, but that didnt go well  :-\.

Title: Re: Buffer from non-conjugated acid/base
Post by: Borek on March 20, 2017, 06:17:20 PM

Start with tutorial, it will guide you through the way the program is organized (menu Help/Tutorial).

Title: Re: Buffer from non-conjugated acid/base
Post by: MR on March 24, 2017, 06:36:50 AM

Is it possible to add a new buffer to the database with the trial version?