Distillation (OCR Gateway GCSE Chemistry: Combined Science)

Distillation of a Mixture

Practical Skills Development

• Safe use of a range of equipment to purify and/or separate chemical mixtures including evaporation, filtration, crystallisation, chromatography and distillation
•  Safe use of appropriate heating devices and techniques including use of a Bunsen burner and a water bath or electric heater
• Use of appropriate apparatus to make and record a range of measurements accurately, including mass, time, temperature, and volume of liquids and gases 

Aim

• To separate pure, clean water from a sample containing water and other substances

Health & Safety Aspects

Materials

• 10 cm³ of an impure water sample
• Bunsen burner
• Tripod
• Gauze
• Heatproof mat
• Clamp and clamp stand
• Conical flask with delivery tube and bung
• Boiling tube
• Ice bath

Diagram showing the apparatus to set-up for a simple distillation experiment

Practical Tip:

• The delivery tube must sit above the filtrate level to prevent cold water being sucked back up the delivery tube after separation, which would break the hot glass
• This experiment can also be done with other mixtures such as orange juice, coca cola or inky water

Method:

1. Add the water sample to the conical flask and set up the apparatus for distillation as shown in the diagram
2. Heat the water using the Bunsen burner until boiling occurs
3. Reduce the heat so that the water boils gently for some time
4. The distilled water will collect in the cooled test tube
5. Collect about 2 cm depth of water in this way, then stop heating
6. Analyse the water you have distilled by determining its boiling point

Results:

The distillate contains pure clean water

Conclusion:

Simple distillation can be used to produce pure water from a sample of impure or contaminated water.