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J248 · PAG4; C7Practical Activity GroupsCore

PAG4: Simple Distillation

In an appropriate mixture such as aqueous ink, simple distillation can recover a volatile solvent while non-volatile components remain in the heated vessel. Heating produces vapour, a cooled region condenses it, and the receiver collects the distillate. Filtration instead removes suitable insoluble particles and does not perform that vapour–liquid separation.

35 min Video by Pearson UK & International Schools Practical Activity Groups
Pearson Edexcel (9-1) GCSE Chemistry Core Practical - distillation and paper chromatographyCurated by Kepler, not produced by us. Watch it before the notes below.
Open on YouTube

Before you start

  • Use your teacher’s tier checklist: this overview can include Higher-only material, and is not a tier-specific revision list.
  • OCR Gateway A separate GCSE Chemistry J248. This is a suitable practical-group example; centres can choose other activities covering the required apparatus and techniques.
  • Recall boiling, condensation and the difference between volatile and non-volatile components.
  • Use the centre’s approved supervised method, apparatus, heating and disposal arrangements. Written preparation does not replace performing and recording the practical activities.

Watch, pause, try

Video by Pearson UK & International Schools. The Pearson demonstration includes ink chromatography as well as distillation. This guide focuses on the vapour–liquid method; the separate chromatography guide develops spot measurements.

Viewing focus: Explain heating, condensation and separate collection

After watching, attempt these questions before opening the answers. You can also use the written lesson below.

After watching 1: What forms the distillate in a suitable setup?

Show answer and reasoning

Condensed vapour. Track the heated component through the vapour path.

After watching 2: Why distinguish coolant from distillate?

Show answer and reasoning

They travel through different parts and have different functions. The jacket removes energy without supplying the intended collected substance.

What you'll be able to do

  • Explain heating, condensation and separate collection
  • Orient a supplied apparatus diagram and measurement point
  • Evaluate recovery and the limits of simple distillation
1

Follow the component being separated

In an appropriate mixture such as aqueous ink, simple distillation can recover a volatile solvent while non-volatile components remain in the heated vessel. Heating produces vapour, a cooled region condenses it, and the receiver collects the distillate. Filtration instead removes suitable insoluble particles and does not perform that vapour–liquid separation.

Use the centre’s approved apparatus, heating and boiling-control arrangements. The apparatus is not a sealed pressure vessel. Identify the connected vapour route and receiver before interpreting a supplied diagram; an apparently similar tube carrying cooling water has a different function from the tube carrying the substance being distilled.

A schematic simple-distillation apparatus shows a heated mixture, a thermometer bulb at the exiting vapour path, a sloping condenser with separate lower coolant inlet and upper outlet, and an open receiver collecting condensed distillate.
Scroll the diagram to see the full view.
Original schematic, not to scale or an assembly procedure. The gold path is heated vapour and the blue continuation represents collected condensate. Cooling water follows a separate jacket path, entering lower and leaving upper. The thermometer samples exiting vapour.
2

Interpret the condenser and temperature reading

A water-cooled condenser removes energy from vapour. In the usual arrangement, coolant enters the lower connection and leaves the upper connection so the jacket remains filled effectively. Cooling water flows in its separate jacket rather than becoming the collected distillate.

A thermometer intended to record the exiting vapour temperature must be positioned appropriately near that vapour path. A bulb immersed in the boiling mixture measures a different location. Record pressure or other relevant conditions when comparing a boiling temperature, and do not turn one approximate reading into a complete composition analysis.

3

Separate volume recovery from a purity claim

Measure the initial and collected liquid volumes if a recovery is required. Losses may arise from liquid remaining in the apparatus or other transfer and collection limitations. A larger recovered volume does not by itself establish a purer sample.

Simple distillation is useful when the volatility differences and mixture make it suitable. Other volatile components can also pass into the receiver, and similar-boiling components may need another separation method. A clear distillate is not proof that all possible contaminants have been removed. State the component and evidence actually assessed.

4

Worked applications

Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.

Example 1A suitable ink sample begins with 20.0 cm³ liquid and gives 12.5 cm³ collected distillate. Calculate volume recovery.
1Recovery = 12.5/20.0 × 100.
2This compares collected with starting liquid volume.
Answer
62.5% volume recovery, not 62.5% purity.
Example 2A supplied apparatus has the thermometer bulb in the liquid instead of near the exiting vapour. What reading should be questioned?
1The bulb is sampling the boiling mixture’s temperature.
2It may not represent the vapour entering the condenser.
Answer
Question any claim that it directly measures the exiting vapour temperature.

Common mistakes to avoid

Calling recovered volume a purity percentage.
Use the definition of the measured ratio.
Treating cooling water as the condensed sample.
Follow the two separate flow paths.

Key takeaways

  • You can explain heating, condensation and separate collection.
  • You can orient a supplied apparatus diagram and measurement point.
  • You can evaluate recovery and the limits of simple distillation.

Apply it in an exam

Question 1: A supplied apparatus has the thermometer bulb in the liquid instead of near the exiting vapour. What reading should be questioned?

Show answer and reasoning

Question any claim that it directly measures the exiting vapour temperature.

  • The bulb is sampling the boiling mixture’s temperature.
  • It may not represent the vapour entering the condenser.

Explore further

Return to this tomorrow

Close the notes and answer from memory. Revisit any explanation you cannot yet reconstruct.

  • Why distinguish coolant from distillate?
  • Does a clear distillate prove complete purity?

Test yourself

Answer a few questions, then review anything you missed.

Next step

Keep practising

Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.

Browse practice topics

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