Theoretical, Actual and Percentage Yield
1. Theoretical Yield
To determine the theoretical yield, multiply the amount of moles of the limiting reagent by the ratio of the limiting reagent and the synthesized product and by the molecular weight of the product.
Example: Theoretical Yield
Therefore, in a perfect experiment, 0.276 g of acetylsalicylic acid will be synthesized.
2. Actual Yield
this is how much product was actually synthesized in the experiment.
Example: 0.135 g acetylsalicylic acid
3. Percent Yield
The percentage yield is the ratio between the actual yield and the theoretical yield multiplied by 100%. It indicates the percent of theoretical yield that was obtained from the final product in an experiment.
The percentage yield can be calculated using the mass of the actual product obtained and the theoretical mass of the product calculated using the balanced equation of the reaction.
Example Problem
In the following reaction, 0.157g of p-acetaminophenol was used to react with 0.486 g of acetic anhydride to produce acetaminophen and acetic acid. The product was purified and acetimophen was extracted. The actual mass of acetaminophen produced was 0.198 g. Determine the theoretical yield and the percent yield of isopentyl acetate.
p-Aminophenol + Acetic anhydride à Acetaminophen + Acetic acid
C6H7NO C4H6O3 C8H9NO2 CH3COOH
Answer
1. Find the limiting reagent
molar mass of p-aminophenol =109.1g/mol
molar mass of acetic anhydride = 102.1 g/mol
moles of p-aminophenol = mass/molar mass
= 0.157g/(109.1g/mol)
= 0.00144 mol
moles of acetic anhydride = mass/molar mass
= 0.486g/(102.1g/mol)
= 0.00476 mol
Theoretical Yield = moles of acetamiophen x molar mass of acetaminophen
= 0.00144 mol x 151.2g/mol
= 0.217 g
Source: http://danielleamorim.tripod.com/
written by: Ian Paulo Parungao
