A 0.338-g sample of an unknown triprotic acid is titrated to the third equivalence point using 33.4 mL of 0.163M NaOH. Calculate the molar mass of the acid.

Question

Quizplus · Accepted Answer

To find the molar mass, first calculate the moles of NaOH used: 0.0334 L × 0.163 mol/L = 0.0054442 mol NaOH. Since the acid is triprotic, it reacts with NaOH in a 1:3 ratio, so the moles of acid is 0.0054442 / 3 = 0.0018147 mol. The molar mass is then 0.338 g / 0.0018147 mol = 186 g/mol.

A 0338-G Sample of an Unknown Triprotic Acid Is Titrated to to the Third