[SoSki1620]

Hello,

I was wondering if there is a way to use the HH equation to calculate a buffer where you are not using a acid/conjugate base pair.  I want to make a 100 mM HEPES solution pH 8.0 using KOH.  I know I can just measure out  100 mM HEPES (i.e 2.3831 g/100 ml solution) and then just pH by adding dropwise KOH till I get to 8.0 but I wanted to know if there is a mathematical approach that works. 

Thanks

[Borek]

calculate a buffer where you are not using a acid/conjugate base pair

Why do you think HEPES buffer doesn't contain conjugate pair? HEPES is an acid that is neutralized by the added KOH.

You can use Henderson-Hasselbalch equation, you can use buffer calculator. Whichever makes the calculation simpler and faster

[AWK]

HEPES is zwiterionic chemical that contains SO₃^- and NH⁺ groups. Its pH is around 5.4. Addition of KOH cause takes H⁺ from tertiary amine and pair of conjugated acid and base is formed.

[Babcock_Hall]

SoSki1620,

I encourage students to use the HH equation to estimate how much KOH (or NaOH) solution that they will need when they make up a buffer.