posted by John on .
A student carried out the synthesis of aspirin, starting with 3.22 g of salicylic acid. After carrying out the reaction, recrystallizing and then drying the product, the student obtained 3.65 g of aspirin. Calculate the percent yield.
I'm pretty sure it's (3.65 g / 3.22 g)*100 = 113.35%.
Is that correct?
Also, could someone please explain what is meant by creating a flow diagram for this experiment?
No, you didn't do the percent yield correctly. You must use the 3.22 g salicylic acid with which you started to calculate how much aspirin you should have obtained if the reaction was 100% efficient. I hastily went through it and it is approximately 4 grams but you need to go through more accurately than I. The value you obtain is the theoretical yield. Then
%yield = (actual yield/theoretical yield)*100 = ??
actual yield is 3.65 grams.
theoretical yield (from my data) is 4 but you will have a slightly different number. A yield of greater than 100% is great if you can get it but there is no free lunch (said another way there is no perpetual motion).