[neel21]

Hi there! I am doing a school experiment wherein I am investigating how different transition metal ions (Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺ and Cu²⁺) affect the rate of catalysis of the oxidation of potassium sodium tartrate by hydrogen peroxide. The website I'm referring to (http://depts.washington.edu/chem/facilserv/lecturedemo/CobaltCatalysis-UWDept.ofChemistry.html)gives the following equation:

NaKC₄H₄O₆ + 5H₂O₂  4CO₂ + 6H₂O + 2OH^- _(aq) + Na⁺_(aq) + K⁺_(aq)

I want to determine quantitatively how much tartrate has been consumed, and I thought that i could do this by calculating the moles of the hydroxyl ion produced in the reaction, for which I thought of titrating the end reaction mixture with 1M HCl so that the titration would not affect the transition metal ions present in solution (these ions were intriduced using their corresponding chloride salts).

However, adding phenolphthalein to the reaction mixture did not give the expected pink colour, which I thought was due to a low hydroxyl ion concentration, and hence titrating with HCl would be futile.

Hence, is there a way that the hydroxyl ion concentration can be determined by titrating these ions selectively against a reagent. Or, is there another way through which I can determine the amount of sodium potassium tartrate used up in the reaction?

Thank You!