Experiment 3: Preparation of Aspirin (Acetyl Salicylic Acid)

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Experiment 3: Preparation of Aspirin (Acetyl Salicylic Acid)

3. Procedure

• Salicylic acid (1.5 g) was weighed using an analytical balance and placed in a conical flask.
• Acetic acid (6 mL) was measured using a measuring cylinder and added to the salicylic acid in the conical flask, followed by 85% sulfuric acid (4 drops).
• The mixture was heated for five minutes at 90 °C in a water bath, and water (20 mL) was added when the mixture was still hot.
• The hot mixture was allowed to stand until crystallization started. The flask was then transferred and cooled in an ice bath, and the crystals were filtered.
• The crystal was recrystallized from hot water by adding hot water (15 mL) until crystals formed as the hot water cooled.
• The crystals were dried by pressing them between filter papers and weighed using an analytical balance.

5. Calculations

• Theoretical Yield of Aspirin: From previous calculations, the theoretical yield of aspirin was $1.96 \text{ g}$.

• Percentage Yield: The actual yield of aspirin obtained was $1.5 \text{ g}$.

  $$\text{Percentage Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\%$$ $$\text{Percentage Yield} = \frac{1.5 \text{ g}}{1.96 \text{ g}} \times 100\%$$ $$\text{Percentage Yield} = 0.7653 \times 100\%$$ $$\text{Percentage Yield} = 76.53\%$$

  The percentage yield was $\boxed{\textbf{76.53\%}}$.

6. Results

• Mass of Aspirin: 1.5 g
• Melting Point: 140 °C
• Percentage Yield: 76.53%