Question

Given four 250 mg tablets of aspirin (90% purity) what volume of 0.50N NaOH is used in the hydrolysis reaction if 10.00 mL of 0.50 N HCl is consumed in the back titration?

Answer 1

Start with the balanced equation.

C9H8O4 aspirin+2OH^-→C7H5O^-3 salicylate+C2H3O^-2 acetate+H2O

Molar Mass of aspirin = 180.158

100/180.158

= 0.554mol

Molar Mass of NaOH = 39.997×0.5×0.554

= 11.07ml