Question

Parts A.6 and B.2. For the standardization of the NaOH solution in Part A.6, the endpoint was consistently reproduced to a faint pink color. However, the endpoint for the titration of the acid solution in Part B.2 was consistently reproduced to a dark pink color. Will the reported molar concentration of the acid solution be too high, too low, or unaffected by the differences in the colors of the endpoints. Explain.

Answer 1

During titration, it is important to carefully observe the color change of solution at the end point. In case of part A, faint pink color indicated that almost exact amount of titrant has been added to the solution of unknown strength and thats why slight change in color was observed and in this case reported molar concentration of acid solution will be close to accurate. In case of part B, dark color indiated that during titration, excess amount of titrant has been added and in this case the reported molar concentration of acid solution will be too low since as per the colour change more amount of acid is required to nutralise the NaOH solution.