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An organic liquid preparation commonly uses reflux to heat a reaction mixture for a sustained period without losing volatile components. Vapour condenses in a vertical condenser and returns to the flask. The top remains connected appropriately to the atmosphere; never seal heated apparatus. Water enters the lower condenser connection and exits at the upper one. Use the approved heating source, quantities and anti-bumping arrangement.
Video by Royal Society of Chemistry. This demonstration focuses on the separating-funnel stage. The written lesson also explains reaction, drying, distillation and yield.
Viewing focus: Explain reflux, washing, drying and distillation as separate operations
After watching, attempt these questions before opening the answers. You can also use the written lesson below.
After watching 1: What is the main purpose of a suitable drying agent?
To remove traces of water from the organic phase. It removes residual moisture after bulk aqueous-layer separation.
After watching 2: Why can a carbonate wash require careful venting?
Acid–carbonate reaction releases CO₂. Gas production can raise pressure in a stoppered funnel.
What you'll be able to do
An organic liquid preparation commonly uses reflux to heat a reaction mixture for a sustained period without losing volatile components. Vapour condenses in a vertical condenser and returns to the flask. The top remains connected appropriately to the atmosphere; never seal heated apparatus. Water enters the lower condenser connection and exits at the upper one. Use the approved heating source, quantities and anti-bumping arrangement.
Esterification is one possible context: an alcohol and carboxylic acid form an ester and water in a reversible reaction. An excess reactant or water removal can influence yield. The precise reaction chosen by the laboratory may differ. Explain which operation forms product and which later operation removes an impurity rather than describing every step as purification.
After the specified cooling and transfer, a separating funnel allows immiscible layers to settle. Identify the intended layer from known densities, composition and, where approved, a small water-addition check; the organic layer is not always on top. Keep both layers until the required product has been securely identified. Drain the lower layer through the tap with the stopper removed, using suitable support.
A wash removes particular soluble impurities. A carbonate wash can remove residual acid and generate carbon dioxide, so the approved procedure requires controlled addition and frequent careful venting away from people; do not build pressure in a closed funnel. A drying agent removes traces of water remaining in the organic phase, which is different from separating a visible aqueous layer. Remove the drying solid before final collection.
Distillation separates a volatile fraction using its boiling behaviour. Collect the specified temperature range and monitor vapour temperature at the condenser entrance. Do not distil to dryness or use a naked flame near flammable vapours. A narrow boiling range may support purity, while infrared or other analytical evidence helps establish identity.
Use the limiting reagent for theoretical yield and measure the isolated dry liquid amount. If converting volume to mass, use the stated density and appropriate temperature. Losses can arise from transfers, product solubility in a wash, incomplete reaction and rejected fractions. A broad collection range may increase mass while decreasing purity; justify the chosen balance.
Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.
Common mistakes to avoid
Key takeaways
Question 1: A learner discards the lower layer because “organic liquids always float”. Explain the fault and a better decision.
Layer position alone does not identify the product.
Check the assessed scope and practical or mathematical requirements.
An external explanation or interactive activity to use alongside the lesson. It may include extension material.
Close the notes and answer from memory. Revisit any explanation you cannot yet reconstruct.
Test yourself
Answer a few questions, then review anything you missed.
Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.