Question

3. 0.69g of salicylic acid was reacted with 0.6g acetic anhydride in the presence of concentrated phosphoric acid to yield 0.80g of acetyl salicylic acid (see below). Determine the limiting reagent and percent yield. C-CH OH COOH CH, COOH CHC Salicylic acid MW 138.12. mp 159C Acetic anhydride Acetylsalicylic acid M W 102.09. bp 140CMW 180.15. mp 128-1370 4. How do you account for the smell of vinegar when an old bottle of aspirin opened?

Answer 1

3. The balanced chemical equation for the neactim betw een Salicylic acid and acetie anhydoide can given be CHH3 Han CH 0-0-CHS + CH3COH Now acconding to the albove equation the matio the no. moles Salicy lie acid and acetic anlydnide No. moles of Salieylic acid 1 1 No of moles f Acetic anlydnide Now, mass of Salicylic acid = 138 12 9mol molan Salieylic a cid 0-69 9 O 69 Salicylie aeid 138-12 mol mel Salieglie acid = 4.99 X 10

Again molan mass & a cetie anhydnide = 102. 09 3 mo Trus, 06 acetie anlydnide 0.6 acctie anlg Fraide 102.09 91mo] m) of acetic onlydnide 5.88 x10 Thus now No P moles Salicy lie acid 4.99 x 10 Acetie anhyo nide 5.38 X103 No Of moles 4.99 1.18 5-88 Thus in the given bacblem acctie anlndnide oemains in excess S0 the limiting ne actant is Salicy lie acid Noro, aceonding to the equatim 138-12 Jf salicylic acid we get 180-15 d acetylsalicylie acid Fnom

Now fram 0.69 3 d Salieylic acid we will get 180-15 X 0 69 138.12 actyl calieylte aeid a cetyl sali eylie acid 0 899 nus the theovetic al yield = 0-899 Given, actual yield =0.80 Achual Yield . Pencent gield Theoretical yield O. 80 O899 88-98 1 Froo significant figures Thus, the percent t yield Aus

4* Vinegan of acetic acid 1s the aqeeous solution a bot11e aspinin gets 9t old it is ass wmed hat it nea in vaboun Salicy 1ie eto with tRe water the ain to produee acid and a cetic acid COOH +t20 +CH3 COOH This acetic acid gives the gmell 4 vinegan
I have given the answer of percent yield as 89 % in two significant figures . You can also use the answer 88.98 % .