help for question 9

Question 9 Sample Problem No. 1 An old stock of a reagent bottle contains the label primary standard grade potassium hydrogen phthalate, KHC3H,O, or KHP. Research student 3x was assigned to verify the purity of the reagent. Student 3X obtained a small portion of the reagent with a mass of 0.4425 g, transferred it into a clean, dry Erlenmeyer flask and dissolved it in 55 mL of distilled water and started titrating it with 0.1250 M NaOH. Unfortunately, student 3X observed that the mixture was over-titrated when the delivery of the titrant was stopped at 14.68 ml. As a remedy, the titration mixture was back-titrated with 1.25 mL or 0.1040 M HCI. Calculate the % KHCH,04(M.M. - 204.23) present in the sample. a A 90.69% KHC HOA B 84.70% KHCH404 78,69% KHC4H4O4 D 39.34% KHC3H404 E 42.35% KHCgH,04