Hello, i would really appreciate it if someone could help me with this problem. I would like to know the pH of citric acid at various concentrations. 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%. From what i have read it has something to do with its pKa value which for citric acid is: 3.06. The formulas i have seen on wikipedia and other places are too complicated for me to solve and although i have found an on-line calculator it seems very inaccurate. http://www.sensorex.com/support/education/pH_calculator.html [Broken] It gives results of: 5% citric acid = 1.87 pH - Lemon juice is 5% and has a pH of around 2.3 Could someone please work these out for me or show me how to do it. p.s. 50g per litre is 5% right? or 50g per 0.950 litre... (of water) Also this is not for my homework.