what is the mass

Question

A 0.8053-g sample of an unknown monoprotic acid is dissolved in water and titrated with standardized sodium hydroxide. The equivalence point in the titration is reached after the addition of 22.97 mL of 0.7474 M sodium hydroxide to the sample of the unknown acid. Calculate the molar mass of the acid.

Answer 1

Molar mass of the acid = grams of acid / moles of acid

We are given the grams of acid, so we need to find the moles of acid. This is done using the data from the titration. Since the unknown acid is monoprotic, we can simply represent it as HA (monoprotic meaning 1 hydrogen). The titration reaction can then be written as...

HA + NaOH ==> NaA + H2O

moles NaOH used = 22.97 mls x 1 L / 1000 mls x 0.7474 mol/L = 0.01717 moles NaOH

moles HA present = 0.01717 mols NaOH x 1 mol HA / mol NaOH = 0.01717 moles HA

molar mass HA = 0.8053 g / 0.01717 moles = 46.90 g/mol