Three aspirin tablets, which were claimed by the manufacturer to each contain 320 mg of aspirin, C6H4(OCOCH3)COOH, were heated gently in 50.00 mL of NaOH solution of concentration 0.5190 mol/ L.
The aspirin tablets reacted according to the equation: C6H4(OCOCH3)COOH(s) + 2NaOH(aq) ? C6H4(OH)COONa(aq) + CH3COONa(aq) + H2O(l)
After cooling, the solution was transferred to a 100.00 mL volumetric flask and the volume was made up to exactly the 100.00 mL mark. Aliquots of 20.00 mL of this solution were then titrated against HCl of concentration 0.1232 mol/L. The mean titre was 24.19 mL.
The equation for the titration is: HCl(aq) + NaOH(aq) ? NaCl(aq) + H2O(l)