Hi. I'm currently an intern in a biology lab and I have a few questions about titration. In the lab we are performing an experiment where the goal is to find the concentration of levulinic acid (H8C5O3). To do this, we decided to titrate the acid with NaOH. Using a KHP standard, we performed the appropriate tests and found that the normality of our NaOH is 1.3570799 N. We then tested it with a pH probe and found that it has a pH of 13.86. First question; is normality = molarity? We then took 25mL of the levulinic acid and titrated it with our NaOH solution. We used phenolphthalein as our indicator, and the whole solution turned pink after the addition of 114.9mL of NaOH solution. Second question; I know that levulinic acid has a carboxylic acid group. Does this mean that there is only one, reactive, "acidic" hydrogen that reacts with the OH- in the titration mixture? Now I am at home and trying to find the concentration of the levulinic acid myself and I'm just unwary/unsure about how to go and find the answer. Here's what I have so far: Using a neutralization reaction chemical equation for H8C5O3 (aq) + OH- (aq) <--> H2O (l) + H7C5O3-(aq) I found that we have 0.15592848051 moles of NaOH (volume of NaOH * normality). If at equilibrium all the moles of reactants fully react with no excess, I assumed then that at the end of the reaction, there are no moles of H8C5O3 and OH- at equilibrium; instead, only negligible moles of H2O and 0.15592848051 created moles of H7C5O3- (aq). From the moles of H7C5O3-, I found the concentration of H7C5O3-. It would be 1.114570982916 M (moles of the anion / total volume). If I were to use this concentration to find the concentration of levulinic acid, then I would: H2O (l) + H7C5O3-(aq) <--> H8C5O3 (aq) + OH- (aq) I C E From this step, I would use an ICE chart. The initial for H7C5O3- would be the 1.11457 M. Then, using the Kb of levulinic acid, (pKa of levulinic acid = 4.78, so then pKb = 14 - 4.78 = 9.22. Kb therefore = 10-9.22) I would have Kb = x2 / (1.11457 - x) Third question: does this all sort out to be okay??? Last, final, kicker question. If I have a pH probe, can I just pH probe the levulinic stock solution we have and then find the number of moles of H+ ions? We know the volume of the stock solution. I know the formula of levulinic acid. If I knew the pH, I could find the [H+], multiply by the volume and get moles of H+. Could the moles of H+ then be used in a 1/8 ratio to find the moles of levulinic acid in stock?? Thank you.