Question: If we mix together 32.2 g of salicylic acids with 15.6 g of acetic anhydride in this reaction we obtain 27.8grams of asprin. What is the percent yield for this reaction? - enter only your numeric answer, do not include the % sign in your answer, do not use scientific notation and enter 3 significant digits
The answer I got was 58.2%. Am I correct?
I got a different number. Post your work and I'll look for the error.
@drbob222
The way I did it was
27.8/47.8 = 58.2
with 47.8g being the total weight of the first two chemicals
That method doesn't work BECAUSE you neglected the other product and since you don't know the amount of acetic acid formed you can't use this method. This is a limiting reagent problem. If you will scroll up to the LR problem I worked above you can see how to do this one also.
salicylic acid + acetic anhydride = aspirin + acetic acid.
The equation is C7H6O3 + C4H6O3 --> C9H8O4 + CH3COOH. You should look this up on Google to make sure I copied it correctly.
To find the percent yield of a reaction, you need to compare the actual yield (the amount of product obtained in the experiment) to the theoretical yield (the maximum possible amount of product calculated using stoichiometry).
To calculate the theoretical yield of aspirin, we need to determine which reactant is limiting. This can be done by comparing the moles of salicylic acid and acetic anhydride. Let's calculate the number of moles for each compound:
Molar mass of salicylic acid (C7H6O3): 138.12 g/mol
Molar mass of acetic anhydride (C4H6O3): 102.09 g/mol
Moles of salicylic acid: 32.2 g / 138.12 g/mol = 0.233 mol
Moles of acetic anhydride: 15.6 g / 102.09 g/mol = 0.153 mol
From the balanced chemical equation for the reaction between salicylic acid and acetic anhydride to form aspirin, we can see that the stoichiometric ratio is 1:1. Therefore, the limiting reactant is acetic anhydride, since it has fewer moles than salicylic acid.
Now, let's calculate the theoretical yield of aspirin. The molar mass of aspirin (C9H8O4) is 180.16 g/mol.
Theoretical yield of aspirin: 0.153 mol x 180.16 g/mol = 27.63 g
Now we can calculate the percent yield using the formula:
Percent yield = (Actual yield / Theoretical yield) x 100
In this case, the actual yield is given as 27.8 grams of aspirin.
Percent yield = (27.8 g / 27.63 g) x 100 = 100.613
Rounding the result to 3 significant digits, the percent yield for this reaction is approximately 100.6%. So, your earlier answer of 58.2% is incorrect.