[dapper]

Hi there. Had a quick question, as my memory of pH is a little shakey. I don't nessecarily need any answers, an outline of the solution would be just fine.
Alright. I have 300ml of a solution at pH 3 and I want it to be pH 9. How much .5m HCl (10ml 3m > 60ml .5m) would I need to add?
I remember something about -log [H+], but not enough to get it figured out. Thanks in advance.

[AWK]

To increase pH you should add base, eg NaOH, and not HCl.
First of all, you should add enough NaOH solution to completely neutralize acid.
After neutralization, at the first approximation you can treat NaCl solution as if it was a pure water, then dilute  NaOH solution using it  to excessed NaOH concentration of 10^-5 M

[Borek]

Why the solution has pH = 3 at start?

It can be strong acid, weak acid or buffer. In every case you need different method for calculation.

[dapper]

Ah, So sorry. It was late I must have made a typo. The solution is pH 3 from the addition of an unknown quantity of citric acid. And I am using .5m NaOH, not HCL. Sorry about that.

[jdurg]

Okay.  Being a weak acid, citric acid will form a bit of a buffer as you neutralize it so you will need to get the Ka for Citric Acid so that you can figure out how much of it you have in there in a solution with a pH of 3.  When my brain wakes up this morning, I'll try and help you along with the rest of it.  

[Borek]

Ah, So sorry. It was late I must have made a typo. The solution is pH 3 from the addition of an unknown quantity of citric acid. And I am using .5m NaOH, not HCL. Sorry about that.

pKa1=3.128
pKa2=4.761
pKa3=6.396

Dangerous area for calculation - two dissociation steps close by. Luckily pH is not between these two pKa values, but below the lower one. Try to assume that only first dissociation step is responsible for pH.

http://www.chembuddy.com/?left=pH-calculation&right=pH-weak-acid-base

If the result is only thing you neeed, try BATE.