A student prepared aspirin (C9H8O4) in a laboratory experiment using the following reaction.
C7H6O3 + C4H6O3 C9H8O4 + HC2H3O2
The student reacted 2.00 g salicylic acid (C7H6O3) with 2.67 g acetic anhydride (C4H6O3). The yield was 2.00 g aspirin. Calculate the theoretical yield and the percent yield for this experiment.
the first one:
2.00g C7H6O3 x (mol C7H6O3/138.12g C7H6O3) x (molC9H8O4/mol C7H6O3) = .014
is this right??
and for the other one i got .026
i changed .014 mol to C9H8O4g as the theoretical
where did i go wrong??
First you didn't add an arrow to separate the products from the reactants. It's easy to get mixed up when you don't know the difference.
Second you didn't carry out the 0.014 far enough. You were given 2.00 g which is three significant figures so you should have at least 3 s.f. for the moles salicylic acid. That is 2.00/138.123 = 0.01448 moles salicylic acid which will produce, as the limiting reagent, 0.01448 moles aspirin. That IS the theoretical yield but its in MOLES. You were given actual yield in grams; therefore, convert 0.01448 moles aspirin to grams (I get 2.609 g and percent yield = (2.00/2.609)*100 = ?? and round to 3 s.f. You should get something like 77% or so.
YOu went wrong by not calculating what .014moles is in grams.
Yield=massproduct/massreactant.
thanks soo much
To calculate the theoretical yield of aspirin (C9H8O4), you need to use stoichiometry. Let's start by balancing the chemical equation:
C7H6O3 + C4H6O3 -> C9H8O4 + HC2H3O2
The balanced equation tells us that for every 1 mole of salicylic acid (C7H6O3), we should get 1 mole of aspirin (C9H8O4). Therefore, the conversion factor is 1 mole C9H8O4 / 1 mole C7H6O3.
Now, let's solve for the theoretical yield:
1 mole C9H8O4 = Molar mass of C9H8O4 = 180.16 g/mol
The given mass of salicylic acid is 2.00 g. We use the molar mass of salicylic acid to convert grams to moles:
2.00 g C7H6O3 x (1 mole C7H6O3 / 138.12 g C7H6O3) = 0.01447 moles C7H6O3
Now, we can use the conversion factor to find the theoretical yield:
0.01447 moles C7H6O3 x (1 mole C9H8O4 / 1 mole C7H6O3) = 0.01447 moles C9H8O4
To convert moles to grams, we multiply by the molar mass of aspirin:
0.01447 moles C9H8O4 x 180.16 g/mol = 2.61 g
So the theoretical yield of aspirin is 2.61 g.
For the percent yield, we'll use the actual yield (given as 2.00 g) and the theoretical yield (calculated as 2.61 g):
Percent yield = (Actual yield / Theoretical yield) x 100
Percent yield = (2.00 g / 2.61 g) x 100 = 76.63%
Therefore, the percent yield for this experiment is approximately 76.63%.
Based on your calculations, it seems there was a minor error in converting moles of C7H6O3 to moles of C9H8O4. Make sure to double-check the conversion factors and perform the calculations accurately.