Question: A solid sample containing only sodium hydrogen oxalate (NaHC2O4) and oxalic acid (H2C2O4) is dissolved in 100.00 mL water. In a first experiment, 10.00 mL of this solution is reacted with 10.00 mL of a 0.100 M solution of sodium hydroxide (NaOH). It takes 7.00mL of a 0.100 M solution of hydrochloric acid (HCl) to titrate the resulting mixture up to the end point indicated by the color change of the thymolphthalein indicator.
Knowing that the tymolphathalein indicator changes color in a pH range of 9.4 to 10.6, the concentration of which basic species then present in solution can be determined by this titration?
Circle all valid applicable and justify your answer briefly
OH- C2O4(2-) HC2O4(-) H2O Cl-
I really don't know how this titration will determine any of these compounds. First of all, if all of it were in C2O4(2-), the solution would still be acidic, due to the low pKa2. So, the only way that the indicator can change color is for all of the compounds to be in C2O4(2-) with excess base. Nevertheless, it is still very confusing. Can someone explain this titration to me?