The preparation of an organic liquid

• Stage 1 making ethyl ethanoate

  1. Put a few anti bumping granules into the pear shaped flask
  2. Add 10cm3 of ethanol, ethanoic acid and sulfuric acid to the flask
  3. On a hot plate place a beaker
  4. Clamp pear shaped flask in the beaker. Add a condenser and set it up for reflux
  5. Add hot water to beaker and turn on hotplate
  6. Boil the mixture for 15 minutes then let it cool
• why do we use reflux?

  So the hot gases would condense back into liquid form to make sure its all used up . Increases yield
• Stage 2- isolation of ethyl ethanoate

  1. After cooling it, add 4.5g of sodium carbonate dissolved in distilled water into a beaker.
  2. Then add the mixture in the pear shaped flask into beaker and stir.
  3. Transfer mixture to a separating funnel and stopper it and invert in atleast 20 times opening the stopcock each time
  4. Allow two layers to separate. Top layer is ethyl ethanoate
  5. Remove stopper and open stopcock and drain out waste then close stopcock
  6. Transfer ethyl ethanoate into a dry boiling tube with anhydrous sodium sulfate. Decant to a clean pear shaped flask
• Stage 3 - purification of ethyl ethanoate

  1. Add anti-bumping granules to pear shaped flask
  2. Set up apparatus for distillation
  3. Place flask in beaker and clamp it
  4. Weigh a clean conical flask on a balance and record mass. Then place conical flask under the receiver
  5. Add hot water to beaker and turn on the hotplate
  6. Record temperature at start of distillation and end of it
  7. Turn of hot plate and cool the mixture
  8. Reweigh the conical flask with the ethyl ethanoate
• Why did the ester form a separate layer to the water?

  Ester has lower density so it would float to the top
• What is the purpose of adding anhydrous sodium sulfate in stage 2?

  To absorb the excess water
• What is the purpose of sodium carbonate in stage 2?

  Reacts with any excess ethanoic acid or sulfuric acid
• Preparation of aspirin

  1. Weigh out salicylic acid into a pear shaped flask
  2. In the fume cupboard, add ethanoic anhydride and then drops of conc sulfuric acid and swirl to mix it.
  3. Set up reflux
  4. Heat the flask until all of the salicylic acid reacts and then for a further 5 minutes
  5. Remove heat and pour down 2 cm^3 of water down the condenser. This causes the flask to boil
  6. After pour contents into cold water in a conical flask and allow crystallisation to happen. Then place in an ice bath
  7. Collect aspirin by suction filtration and wash and dry the product
• Why do you add some water down the condenser?

  It would hydrolyse any excess ethanoic anhydride left in the flask
• Purification of aspirin (stage 2)

  1. Scrape sample of dried impure aspirin from filter paper and record mass
  2. Measure out 7cm of ethanol using a measuring cylinder into a boiling tube.
  3. Using spatula , put the aspirin into the boiling tube and place boiling tube in a water bath
  4. Stir until all of aspirin is dissolved
  5. Allow conical flask to cool and then filter of any purified solid and allow it to dry on filter paper
• Suggest how anti-bumping granules prevent bumping

  Because they form small bubbles and stop large bubbles from forming