Chemistry

posted by .

Aspirin can be prepared by the reaction of salicylic acid with an excess of acetic anhydride, using phosphoric acid as a catalyst. Once the aspirin is formed, it is precipitated from the reaction mixture by adding water and filtering. The solid aspirin obtained in this way is contaminated with acetic acid. To purify it, it will be recrystallized from an ethanol-water mixture. Recrystallization is a commonly-used method for the purification of solids. In this case it is done by dissolving the impure aspirin in a hot ethanol-water mixture; purified aspirin will recrystallize upon cooling the solution.

If the recrystallization step was skipped, would this result in an increase or decrease of the apparent percent yield or have no effect?

I feel that it would result in an increase in the apparent percent yield because the actual yield would be larger than what it would have been had the recrystallization been carried out.

Is this reasoning correct?

Also, from the above description of the experiment, what does "The solid aspirin obtained in this way is contaminated with acetic acid" mean in simple terms?

  • Chemistry -

    I feel that it would result in an increase in the apparent percent yield because the actual yield would be larger than what it would have been had the recrystallization been carried out.

    I think your reasoning is ok and the answer is ok. If you have used all of the salicylic acid, then the only thing left is acetic acid and product. Technically, one might be able to air/heat dry the material to drive off the acetic acid and the yield would be better because of the increased amount of the product. You ALWAYS lose some product in a crystallization. What would bother me more, but the problem doesn't address it, is that some of the salicylic acid may not have reacted so the product could be contaminated with some of the starting material, also, which would increase the apparent yield, too. From the statement in the problem, the contamination with salicylic acid has not been addressed; it assumes, I suppose that all of the S.A. will be used and the only contaminant is the excess of acetic acid used in the course of the experiment.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. chemistry

    Asprin, C9H8O4, is prepared by reacting salicylic acid, C7H6O3, with acetic anhydride, C4H6O3, in the reaction C7H6O3(s) + C4H6O3(l) -> C9H8O4(s) + C2H4O2(l) A student is told to prepare 45.0 g of aspirin. She is also told to use …
  2. Chemistry

    ASpirin, c9h8o4, is prepared by reating salicylic acid, c7h6o3, with acetic anhydride, c4h6o3, in the reaction. c7h6o3 + c4h6o3---> c9h8o4 + c2h4o2 A student is told to prepare 45.0 g of aspirin. she is also told to use a 55.0 % …
  3. AP Chemistry

    Aspirin (C9H8O4) is synthesized by reacting salicylic acid (C7H6O3) with acetic anhydride (C4H6O3). The balanced equation is given below. C7H6O3 + C4H6O3 C9H8O4 + HC2H3O2 (a) What mass of acetic anhydride is needed to completely consume …
  4. Chemistry

    If 0.150 moles of salicylic acid and execs acetic anhydride are used during a synthesis of aspirin, how many grams of aspirin will be obtained if the reaction gives a 38% yield?
  5. chem

    Aspirin, C9H8O4, is produced from salicylic acid, C7H6O3, and acetic anhydride, C4H6O3: C7H6O3 + C4H6O3 --> C9H8O4 + HC2H3O2 a. How much salicylic acid is required to produce 1.5 x 10^2 kg of aspirin, assuming that all of the salicylic …
  6. Chemistry

    Aspirin is prepared by heating salicylic acid, C7H6O3, with acetic anhydride, C4H603. The other product produced is acetic acid, C2H402. C7H6O3+C4H6)3->C9H8O4+C2H4O2 What is the theoretical yield in grams of aspirin, C9H8O4, when …
  7. chemistry (Pls Bob check for me)

    Aspirin c9h8oh molar mass = 180.1g/mol can be prepared by the reaction of salicylic acid c7h603 molar mass = 13801 g/mol with acetic anhydride c6h603, according to the following equation. A chemist starts with 2 gram of salicylic acid …
  8. chemistry

    Show the calculation of (1) the expected grams of aspirin (C9H8O4) formed in the reaction of 2.7 grams of salicylic acid (C7H6O3) with excess acetic anhydride and then show the calculation of (2) the % yield if the actual yield of …
  9. Chemistry

    Aspirin can be prepared in the chemistry laboratory by the reaction of salicylic acid with acetic anhydride. What volume of acetic anhydride is required to produce one killogram of aspirin assuming 100%yield
  10. chem

    A chemist is commissioned to produce twenty pallets of aspirin: C7H6O3 (salicylic acid) + C4H6O3 (acetic anhydride) → C9H8O4 (aspirin) +C2H4O2 (acetic acid) Given a bottle contains 500 tablets (each containing 325 mg of aspirin). …

More Similar Questions