[donniedarko]

Hello,
I am an undergrad working as a volunteer in a research lab.  This is not a homework problem, but a real-world question.  It's been a few years since I took general chemistry and can't seem to figure out what should be a very simple problem, even after consulting my old textbooks. 

I have 11ml of 50 mM PO4 buffer at pH 6.   I need to bring it up to a pH of 8, and I have a stock solution of 5M NaOH which I can use to do so.  How many µl of NaOH should I add to the PO4 buffer to change it from pH6 to pH 8?  It seems a lot of guys in the lab just titrate until the pH meter says they've reached the desired pH, but I'd like to be able to calculate how much base to add before attempting a titration.

Thanks in advance! 

Incidentally, I tried Henderson Hasselbach, setting it up as 8 = 6 + log (base) / (.05M PO4), but I'm not sure if that's the correct approach. 

[Borek]

Find out what acid and conjugate base you have in your buffer and in what ratio.

Find out what acid and conjugate base you need in pH 8.0 buffer.

Assuming NaOH reacts quantitatively with acids present, starting from the strongest, then the weaker ones, calculate how much NaOH you need.

[dzoys]

it has nothing to do with the logarithms


what is it you are testing for?

what u are asking for is like an hour lecture and 10 homework problems... here is a summary

http://www.tutorvista.com/answers/how-to-calculate-titrations/21506

[Borek]

it has nothing to do with the logarithms

How are you going to calculate pH without use of logarithm?

what is it you are testing for?

Have you actually read the post, or are you just trolling?