What it does
The separation lab is a virtual bench for separating mixtures. Pick a mixture, then tap a method: handpicking, sieving, a magnet, adding water, settling and pouring off, filtration, evaporation, crystallisation, distillation, fractional distillation, a separating funnel, sublimation, paper chromatography or a centrifuge. A small picture of the apparatus shows the method at work, and the containers below show what you now have. A tick marks a container that holds one pure substance.
Some mixtures need one method; others need a plan. Sand and salt look alike and are the same size, so you must add water, filter out the sand and then evaporate the salt water. Every wrong choice tells you why it fails, which is the real lesson: each method uses one property, such as size, magnetism, solubility, density, boiling point or how far a dye travels up paper.
It follows the school topics on mixtures: pure substances and mixtures and how to separate them (Class 9 Science, exploring mixtures and their separation; Class 8 Science, elements, compounds and mixtures) and the purification methods in Class 11 Chemistry (organic chemistry basics: sublimation, crystallisation, distillation, fractional distillation and chromatography). Before this, see how particles change state in states of matter and why a liquid boils at a fixed temperature in heating curve; for real chromatography plates use TLC Rf calculator.
How to use it
- Choose a Level. Class 9 keeps to what each method does. Class 11 adds the boiling-point rule for distillation, Rf values and notes on sublimation and crystallisation.
- Pick a Mixture from the list. The note under it gives a clue.
- When there is more than one container, choose which one to work on with the numbered buttons (or tap the container in the picture).
- Tap a method. The pill says whether it worked, partly worked or did nothing, and the text explains why.
- Keep going until every substance you want is in its own container with a tick. Undo takes back one step; Start again resets the mixture.
Worked example
Choose Sand and salt. A sieve fails (the grains are the same size) and so does a magnet (neither is magnetic). Tap Add water and stir: the salt dissolves and the sand does not. Tap Filtration: container 1 is the sand left on the paper (the residue), container 2 is salt water (the filtrate). Pick container 2 and tap Evaporation: the water goes into the air and salt is left in the dish. The page shows Recovered pure: 2 of 2 in 3 steps.
Now choose Alcohol and water and tap Distillation. The boiling points, 78 °C and 100 °C, are only 22 °C apart, so lots of water vapour comes over too and both containers keep a trace of the other liquid. Start again and tap Fractional distillation: the thermometer stays at 78 °C while the alcohol comes over, then climbs to 100 °C, and both liquids come out pure.
Tips
- A dissolved solid passes through filter paper and never settles. To get it back you must remove the liquid: evaporation (liquid lost) or distillation (liquid kept).
- Crystallisation gives purer crystals than evaporating to dryness, because soluble impurities stay in the left-over liquid.
- Chromatography is for very small amounts: it tells you what is in a mixture of dyes rather than giving you a jar of each.
FAQ
Why does settling only partly work for muddy water? Clay particles are so fine that they settle very slowly, so the water you pour off stays cloudy. Filtration or a centrifuge does better.
Is cream really separated by a centrifuge? Yes: dairies use spinning separators. The fat drops are lighter than the rest of the milk and collect in the middle while the skimmed milk is thrown outwards.
Is anything stored? No. The questions are made fresh in your browser and nothing is saved or sent.
Where the numbers come from
- Methods of separating mixtures (handpicking, sieving, magnetic separation, sedimentation and decantation, filtration, evaporation, crystallisation, distillation, fractional distillation, separating funnel, sublimation, paper chromatography, centrifugation) and Rf = distance moved by spot ÷ distance moved by solvent: standard school chemistry found in any textbook.
- Boiling points rounded to the nearest degree: acetone 56 °C, ethanol 78 °C, water 100 °C (standard pressure). The 25 °C rule of thumb for simple versus fractional distillation is a common teaching guide, not an exact limit. The dye Rf values are made-up teaching values.
- The rules were checked against hand-worked examples for every mixture: the textbook method separates it, and the wrong methods fail with the reason a student would give.
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-09.