posted by kelis .
A 0.5130 g aspirin tablet which was dissolved in 95 percent ethanol required 27.98 mL of 0.1000 M NaOH for neutralization. Then an additional 42.78 mL of 0.1000 M NaOH was added and the soln was heated to hydrolyze the aceytlsalicyclic acid. After the reaction mixture was cooled, the excess base was back-titrated with 14.29 mL of 0.1056 M HCL. How many grams of acetylsalicylic acid are in the tablet? What % w/w of the tablet is acetylsalicyclic acid?
The first titration neutralizes the ASA. The hydrolysis and back titration determines the amount of acetic acid produced in the hydrolysis and indirectly, the amount of ASA initially. Each can be used to determine the percent ASA. Therefore, I can obtain two answers for the ASA. Do you have any instructions as to which is more accurate? Or to take the average of the two results? Anything to help here. I can show you how to do the two but they differ by about 1%.