1.15g of acetylsalicylic ia recovered from an aspirim synthesis reaction that began with 2g of salicylic acid, what would be the percentage yield for the preparation? show your computations
SA = salicylic acid
ASA = aspirin
mols SA = grams/molar mass = ?
mols ASA produced = mols SA
grams ASA = mols ASA x molar mass ASA. This is the theoretical yield (TY)
Actual yield (AY) either 1.15 or 0.15 depending upon how you read the question.
% yield = (AY/TY)*100 = ?
To calculate the percentage yield for the preparation, we need to divide the actual yield (in this case, 1.15g) by the theoretical yield and multiply by 100.
To find the theoretical yield, we need to determine the amount of acetylsalicylic acid that would be formed if the reaction went to completion.
First, let's determine the molar masses of salicylic acid (C7H6O3) and acetylsalicylic acid (C9H8O4):
- Salicylic acid: 12.01 g/mol (C) + 1.01 g/mol (H) + 16.00 g/mol (O) x 3 (for three oxygens) = 138.12 g/mol
- Acetylsalicylic acid: 12.01 g/mol (C) + 1.01 g/mol (H) x 8 (for eight hydrogens) + 16.00 g/mol (O) x 4 (for four oxygens) = 180.16 g/mol
Next, we can calculate the theoretical yield using the stoichiometry of the reaction. Assuming the reaction is complete, one mole of salicylic acid will react with one mole of acetic anhydrate (the other reactant) to produce one mole of acetylsalicylic acid.
Now let's calculate the number of moles of salicylic acid:
- Moles of salicylic acid = mass of salicylic acid / molar mass of salicylic acid
- Moles of salicylic acid = 2g / 138.12 g/mol = 0.0145 mol
Since the mole ratio between salicylic acid and acetylsalicylic acid is 1:1, the theoretical yield will be the same as the moles of salicylic acid.
Therefore, the theoretical yield of acetylsalicylic acid is 0.0145 mol.
Now let's calculate the percentage yield:
- Percentage yield = (actual yield / theoretical yield) x 100
- Percentage yield = (1.15g / (0.0145 mol x 180.16 g/mol)) x 100
- Percentage yield = (1.15g / 2.6132g) x 100
- Percentage yield = 44.01 %
So, the percentage yield for the preparation is approximately 44.01%.