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Titration Error


A student used an acid-base titration to determine the molar mass of a solid weak monoprotic acid like $KHP$. This student titrated a weighed sample of the solid acid, after dissolving it in water in a flask, with a standardized $NaOH$ solution in a buret.

Which of the following could explain why the student obtained a molar mass that was too large?


Some of the solid monoprotic acid still remained on the weighing paper and was not transferred to the flask for titration.


More water was used to dissolve the solid monoprotic acid than what the lab called for.


Addition of some base beyond the endpoint of the titration.


The buret was not conditioned with the standardized $NaOH$ solution, but with distilled water at the beginning of the titration.