RP10-B-Preparation of a pure organic liquid

Question 1

Preparation of Propyl Ethanoate

Question 2

Describe the method used for this reaction

Answer 2

1. Add 5 ml of propanol to 5ml of glacial acetic acid (Conc. ethanoic acid) in a boiling tube
2. Add 8 drops of concentrated sulphuric acid to the oiling tube
3. Cover the top of the boiling tube with clingfilm
4. Carefully place the boiling tube in a water bath (60’) for 15 minutes
5. Half fil a small beaker with sodium carbonate solution (0.5moldm-3) that has been saturated with sodium chloride
6. remove the boiling tube from the water bath and carefully pour a height of about 1.5cm of your sodium carbonate solution into the tube.
7. pour the boiling tube contents into a separating funnel (ensure the tap is closed on the separating funnel). Wash the boiling tube with further small quantities of sodium carbonate solution and transfer all washings into the separating funnel
8. stopper the separating funnel, invert and gently swirl for a few seconds.
9. release the pressure by opening the inverted separating funnel tap, close the tap and then gently swirl again for a few seconds.
10. repeat step 9 two more times
11. turn over the separating funnel, so that the closed tap is at he bottom. remove the stopper and allow the mixture to settle for 5 minutes.

Question 3

What is the role of the sodium carbonate in this experiment?

Answer 3

Neutralises excess acid
Saturated sodium chloride solution – helps separate the organic layer from the aqueous layer

Question 4

How can TLC be used to confirm that your propyl ethanoate is pure?

Answer 4

One spot on the chromatogram