I'm not looking for an indepth howto, I can look that up..... I've only taken up to High School chemistry but I have intentions to research further into chemistry on my own before I get into university. Say I have a solution of a known quantity and known pH, and I want to add a currently unknown amount of another solution to it, which I know the pH.... How do I calculate the amount of the second solution to add to get the pH to a specific level.... I'm not looking for a how-to if it's a long answer, just what this method is called so I can look it up more specifically. Also what's the method called when you calculate the pH of a diluted solution. Like say you have Acetic Acid(ph 2.4) in a %5 aqueous solution... Meaning only 5% of the solution is Acetic Acid.. How would the Ph of the solution be calculated?