An aspiring tablet is boiled in an attempt to dissolve an aspirin tablet which weighs 392 mg for several minutes. Titration of .050M NaOH requires 44.37mL. What is the apparent %ASA in the tablet. Is there a problem here? If so, what is likely to have happened?
(Hint: can't use the EMM formula (Effective Molar Mass) (Molar mass of Aspirin: 180.15 g, pKa= 3.50) (Molar mass of salicylic acid is 138.12 g, pKa=2.99)
2007-03-28 02:41:07 · 1 answers · asked by horn.nicole 2 in Science & Mathematics ➔ Chemistry
mole NaOH= M*V= 0.050*44.37*10^-3 = 2.22*10^-3
You would expect that to correspond to
mass= mole*MW= 2.22*180.15 =399.9 =400 mg
apparently boiling caused some hydrolysis of the acetyl salicylate forming some acetic acid which reacted with the NaOH giving you an error in the titration.
2007-03-28 03:25:40 · answer #1 · answered by bellerophon 6 · 0⤊ 1⤋