What is the concentration of the tartaric acid solution?

Question

A titration of 53.0 mL of a tartaric acid (H₂C₄H₄O₆) solution of unknown concentration with 0.805 M LiOH requires 32.0 mL to reach the second equivalence point. What is the concentration of the tartaric acid solution?

Answer 1

Tartaric acid is a dicarboxylic acid (has 2 acid hydrogens).

The balanced equation for reaction with LiOH to reach the 2nd equivalence point is as follows:

H₂C₄H₄O₆ + 2LiOH ==> Li₂C₄H₄O₆ + 2H₂O ... balanced equation

moles LiOH used = 32.0 ml x 1 L / 1000 ml x 0.805 mol / L = 0.02576 mols LiOH used

moles H₂C₄H₄O₆ present = 0.02576 mols LiOH x 1 mol H₂C₄H₄O₆ / 2 mols LiOH = 0.01288mols H₂C₄H₄O₆

[H₂C₄H₄O₆] = 0.01288 mols / 53.0 ml x 1000 ml / L = 0.243 moles / L = 0.243 M (3 sig. figs.)