Problem: A 0.446-g sample of an unknown monoprotic acid was titrated with 0.105 M KOH and the resulting titration curve is shown in the figure.Determine the molar mass of the acid.

FREE Expert Solution

Recall that at the equivalence point of a titration:


moles acid=moles base


Also, recall that moles = molarity × volume


molesacid=MVbase


Volume at equivalence point = 38 mL KOH

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Problem Details

A 0.446-g sample of an unknown monoprotic acid was titrated with 0.105 M KOH and the resulting titration curve is shown in the figure.
A graph of pH versus Volume of base added (mL). At 0 mL of base the pH starts out at about 3 then steadily increases as base is added. At about 35 mL of base added the graph is almost vertical from a pH of about 6 to 11. As more base is added past 35 mL the pH goes back to a steady increase up to 100 mL where the pH is about 13.

Determine the molar mass of the acid.

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