Question

1.16 g aspirin was synthesized from 1.03 g salicylic acid and 2.00 mL of acetic anhydride.


Calculate the mass percentage yield.

Molar mass of salicylic acid = 138.12 g/mol

Molar mass of aspirin = 180.16 g/mol

Density of acetic anhydride = 1.0820 g/mL

(Hint: It can be calculated by using actual / theoretical x100%)

Answer 1

Answer:

The percentage yield is 85%

Explanation:

Step 1: The balanced equation

2 C7H6O3 +  (CH3CO)2CO → 2 C9H8O4 + H20

Step 2: Given data

1.03 grams of salicylic acid

2.00 mL of acetic anhydride.

1.16 g aspirin was synthesized

Step 3: Calculated moles of salicylic acid

Number of moles of salicylic acid = mass of salicylic acid / Molar mass of salicylic acid

Number of moles of salicylic acid = 1.03 grams / 138.12 g/mole

Number of moles of salicylic acid =0.0075 moles

Step 4: Calculated moles of acetic anhydride

Density = 1.0820 g/mL

mass of acetic anhydride = 1.0820 * 2 mL = 2.164 grams

Number of moles = 2.164 grams / 102.09 g/moles

Number of moles = 0.0212 moles

Step 5: find the limiting reactant

C7H6O3 is the limiting reactant, there will react 0.0075 moles

Since for 2 moles C7H6O3 consumed, we need 1 mole of (CH3CO)2CO to produce 2 moles of C9H804

So for 0.0075 moles C7H6O3 consumed, we produce 0.0075 moles of C9H8O4

Step 6: Calculate mass of aspirin

mass of aspirin = 0.0075 moles * 180 g/mole = 1.35 grams

Step 7: Calculate the mass percentage yield

(1.16 grams / 1.35 grams) * 100% = 85 %

The percentage yield is 85%