When synthesizing aspirin in the lab((Mixed 2g salicylic acid, 5mL acetic anhydr

Question

When synthesizing aspirin in the lab((Mixed 2g salicylic acid, 5mL acetic anhydride, 5 drops concentrated sulfuric acid, added distilled water after heating)). . . . . . . What is the theoretical yield of aspirin since salicylic acid is the limiting reagent?(please show calculation used) . . . . . . . What is the new type of compound formed in this?(i.e. an amide, ect?)

Explanation / Answer

here is examlpe which help u [EXAMPLE] Show by calculation which reactant was the limiting reagent in this synthesis? Why was the other reactant used in excess? (tip; density of ethanoic anhydride= 1.08g cm^-3) 2g of salicyclic acid, 4cm^3 of ethanoic anyhdride a few drops of concentrated sulphuric acid 2cm^3 of distilled water...after reaction subsided add a further 40cm^3 of water. Please may somebody help me as i have no idea where to start! much appreciated, laura x {ANSWER} So first you have to understand the reaction that takes place. The ethanoic anhydride in the presence of water turns into ethanoic acid, or acetic acid. You can sort of write the reaction as follows: SA (sal acid) + HAc (acetic acid) --> acetylsalicylic acid (aspirin) Note that 1 mole of SA reacts with 1 mole of HAc to give the product. Now calculate how many moles of each you have, and the one that is the smallest, is LIMITING, because once you run out of that, the reaction is over. Moles of SA = 2 gm/138gm/mol = 0.014 moles of SA Moles of HAc = 4 cc x 1.08gm/cc = 4.32g/102gm/mol = 0.042 moles Therefore, the lowest one is SA so that is limiting. The other was used in excess to be sure that ALL of the SA was converted to product

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