Preparation of Aspirin

PRAC 2: Preparation of Aspirin                                                          

INTRODUCTION: For this experiment, the purpose was to see how much aspirin was made from the ingredients used. It was predicted that 2 grams of aspirin will be produced.

AIM: To see how much aspirin was made from the ingredients used in this experiment.

HYOPTHESIS: It was predicted that 2 grams of aspirin will be produced.

INDEPENDENT VARIABLE:  There is no independent variable.

DEPENDENT VARIABLE: There is no dependent variable.

CONSTANT: Everything stays the same as this is a straightforward experiment.

CONTROL: There is no control.

APPARATUS:

• 3 grams salicylic acid
• 10 ml acetic anhydride
• 1 ml concentrated sulphuric acid
• 250 ml conical flask
• 10 ml measuring cylinder
• Filter flask
• Large watchglass
• Glass rod
• Buchner funnel
• Filter paper
• 130 ml ice water

METHOD:

1. Place a weighed mass of 3 grams salicylic acid in a conical flask.
2. In a fume cupboard, add 10 ml of acetic anhydride and 1 ml concentrated sulphuric acid to the flask swirl the mixture until all the solid has ‘dissolved’. Then take the flask out of the fume cupboard.
3. Allow the mixture to cool and add 100 ml of ice water. The resulting oil should be ‘scratched’ with a glass rod to induce crystal formation.
4. Collect the solid by filtering in a Buchner funnel, wash with ice water. Allow the crystals to dry and then weigh them.

DATA AND RESULTS: The amount of aspirin produced was 2.413 mg.

QUESTIONS/ DISCUSSIONS:

1. What is a catalyst? In this experiment which chemical acts as a catalyst?

A catalyst is a chemical substance which speeds up the reaction without involving in the reaction. In this experiment, sulfuric acid is the catalyst.

1. Sulfuric acid is a strong acid, a strong oxidant and a dehydrating agent. Define dehydrating agent. Could sulfuric acid act as a dehydrating agent in this experiment? Explain.
   A dehydrating agent is a substance that is capable of removing water from a material or drying material.
2. What are binders and fillers? Explain why they are added to aspirin tablets.
   Binders bind the ingredients of the tablet together and fillers add volume to the tablet. It allows a small amount of active ingredient to be accurately dispensed.
3. A typical aspirin tablet contains 300 mg of aspirin. How many tablets could you make from your own preparation?
   About 8 aspirin tablets could be made from the preparation.
4. State an improvement that could be made to this experiment.
   Giving plenty of time for the mixture to cool.
5. Outline 3 safety precautions for this experiment.

• Wear safety glasses and laboratory coats when handling with acetic anhydride.
• Wipe away any acid spillages.
• Do not breathe in the fumes.

ALTERATIONS AND IMPROVEMENT: Many improvements could be made to this experiment such as:
- Making sure all the solid dissolves when swirling the mixture.
- Giving enough time for the mixtures to cool and the crystals to dry.
- Carefully scratching the resulting oil to induce crystal formation.