help mi pliz- i need the answer b4 6:30- help pliz?

Question

A 0.5130 g of aspirn tablet which was dissolved in 95% ethanol required 27.98L of 0.100 M NaOH for neutralization. Then an additional 42.78mL of 0.10M NaOH was added and the solution was heated to hydrolyze the acetylsaclicylic acid. After the reaction mixture was cooled , the excess base was back-titrated with 14.29 mL of 0.1056 M HCl.
a)how many grams of acetylsaclicylic acid are in the tablet?
b)What % w/w of the tablet is acetylsaclicylic acid?

Answer 1

You need to know that there is one dissociable H+ that can be neutralized with base in acetylsalicylic acid. For every 1 mole of H+, 1 mole of OH- is needed for neutralization.

Also, I am sure that the initial neutralization was with 27.98mL not L of NaOH.

0.5130g aspirin tablet contains x grams of acetylsalicylic acid, which will be determined by calculating how many moles of OH- are used to neutralize the acid

Hydrolyzing the acetylsalicylic acid breaks the ester bond to make salicylic acid....I don't think you use any of the other info than 27.98mL NaOH since the rest of the info is about the hydrolysis of ester bond, not about the neutraliztion.

Hope that helps.

w/w% is simply (grams of acetylsalicylic acid/grams of aspirin tablet) x 100