Report Sheet C. Preparation of Aspirin C.I Mass of flask Mass of flask and salic
ID: 556375 • Letter: R
Question
Report Sheet C. Preparation of Aspirin C.I Mass of flask Mass of flask and salicylic acid Mass of watch glass Mass of watch glass and crude aspirin product C.2 Calculations C.3 Mass of salicyclic acid C.4 Possible (maximum) yield of aspirin Show calculations.) C.5 Mass of crude aspirin C.6 Percent yield Show calculations. C.7 Melting point (C) of aspirin product (optional) Questions and Problems Q.4 Write the structural formula for aspirin. Label the ester group and the carboxylic acid group. Q.5 In the preparation of aspirin, water is added to the reaction flask. Why?Explanation / Answer
(Mass of flask - Mass of flask with salicylic acid) gives mass of salicylic acid taken.
(Mass of watch glass - mass of watch glass with crude product) gives mass of crude product.
Aspirin is the acetylated salicylic acid and is usually prepared by condensing acetyl chloride or acetic anhydride with salicylic acid to yield the crude aspirin product. If the no.of moles of both reactants are calculated as (mass of compound/molecular mass of compound), the compound with least no.of moles will completely react leaving that many moles of aspirin product only, leaving the other compound, in more no.of moles unreacted. This limiting reagent's no.of moles is equal to the no.of moles of the product ,which is the theoretical yield of aspirin.
From the mass of crude product, % yield is calculated as (mass of crude product/theoretical yield)x100.