Required Practical 5 - Distillation of a product from a reaction

Give the 7 step method to Distil a product from a reaction

1. Using a measuring cylinder, measure out 12 cm³ of solution of acidified Potassium Dichromate and pour into a round bottom flask

2. Using a measuring cylinder measure 2 cm³ of Ethanol

3. Use a dropping pipette add Ethanol dropwise to the round bottom flask

4. Add a few anti-bumping granules to the round bottom flask

5. Set up distillation apparatus placing the round bottom flask in a hot water bath

6. Heat the water bath using a Bunsen burner and collect approx 5 cm³ of distillate

7. Use Fehlings/Tollens reagent to test the distillate or heat to boil and compare to reliable data values

Give 3 ways to decrease Uncertainty

1. Place thermometer in the path of the vapours and mouth of the water jacket outlet

2. Keep system sealed - not air tight - to ensure vapour isn’t lost

3. Heat with water bath to ensure constant temp

What safety issue could you take when handling the acidified Potassium Dichromate?

Acid skin contact:

• Wear glasses + goggles

Why do we add Anti-Bumping granules?

Promote smooth boiling by allowing site for bubbles to form - preventing violent bubbling/boiling

Dehydration of Cyclohexanol to Cyclohexene

Dehydration of Cyclohexanol to Cyclohexene

What 4 stages are there of the Dehydration of Cyclohexanol to Cyclohexene?

1. Preparation of Cyclohexene

2. Distillation

3. Separation

4. Idenitication

Give the 3 step reflux method of the Dehydration of Cyclohexanol

1. Add 8 cm³ of Phosphoric acid to a volume of cyclohexanol in a round bottom flask dropwise + swirl

2. Add anti-bumping granules

3. Heat under reflux (70 degrees celsius) for 15 minutes

Give the 4 step distillation method of Cyclohexanol dehydration

1. Transfer the heated solution to a round bottom flask and distillation apparatus

2. Heat with a water bath and heat, ensure its sealed but not air tight

3. Collect cyclohexene in flask through condensing jacket

4. Stop reaction when the solution in the round bottom flask forms white fumes

Give the 2 step separation method of Cyclohexanol dehydration

1. Transfer the cyclohexene solution from the flask and add aqueous Sodium Carbonate to it in a separating funnel

2. Invert + elute the aqueous layer

How can we identify that the solution is Cyclohexene? (2)

1. Use Br water (change from orange to colourless)

2. Boil + compare to known Boiling point of Cyclohexene

Give 2 ways to decrease uncertainty in Cyclohexanol dehydration

1. Water bath for constant temperature

2. Use constant volumes