Separating mixtures: decanting, filtration, evaporation, separating funnel, distillation

Integrated ScienceMatter & MaterialsAges 11–12Virtual lab

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Use with my class

Choose a mixture (sand–water, salt–water, cooking oil–water, ethanol–water, or muddy water) and a separation method, watch the process play out, then check the result: fully separated, only partly separated, or not separated at all, and why. Students can switch methods right on the toolbar to find the one that fits the substances' properties. The More methods screen adds handpicking, threshing, winnowing (the wind carries the light husk away from the grain), sieving by particle size, churning cream into butter, sublimation of ammonium chloride, centrifugation of milk at a chosen speed, and coagulating muddy water with alum before decanting; each names the property it uses. The Plan screen lets students order the steps that separate a mixture of several substances.

Lesson: Separation methods: settling and decanting, filtration, evaporation, separating funnel, distillation; based on the substances' different properties

What it shows

A mixture can be separated because its components keep their own properties, and each method uses one difference. Decanting and filtration use insolubility and density, evaporation recovers a dissolved solid, a separating funnel splits immiscible liquids and distillation uses boiling points. Other methods use size (sieving, handpicking), weight in a wind (winnowing after threshing), density in a fast spin (centrifuging cream from milk), sublimation (ammonium chloride from salt), coagulation (alum makes fine clay settle) and the clumping of fat (churning butter). Several methods in the right order separate a mixture of many substances.

How to use

On the first screen pick a Mixture, predict the right Separation method, then watch and read the verdict. On More methods choose a method, set its variable (Wind speed, Sieve hole size, Cream temperature, Heating temperature, Spin speed and Spin time, or Alum dose) and press Run; for handpicking, tap the stones. Results go into the table; the centrifuge and alum methods have tasks. On Plan a separation choose a Mixture to separate, add steps in order, and press Check plan to see what each step does.

Parameters you can change

Mixture Sand and water, Table salt dissolved in water, Cooking oil and water, Ethanol (alcohol) and water, Muddy water (silt)
Separation method Settle & decant, Filtration, Evaporation, Separating funnel, Distillation
Animation speed 0.5–3 ×
Show suggested method
Screen Filtration, evaporation, distillation, More methods, Plan a separation
Method Handpicking, Threshing, Winnowing, Sieving, Churning, Sublimation, Centrifugation, Alum, then decanting
Wind speed 0–10 m/s
Sieve hole size 0.5–10 mm
Cream temperature 4–30 °C
Heating temperature 100–400 °C
Spin speed 0–6000 rpm
Spin time 1–30 min
Alum dose 0–60 mg/L
Mixture to separate Sand, salt and ammonium chloride, Harvested wheat (with stones), Muddy salty water, Whole milk

Questions to explore

Why can filtration not separate salt from salt water, and which method can?
Which property of ethanol and water makes distillation work for this mixture?
Which method separates cooking oil from water most simply, and which liquid leaves the funnel first?

Common questions

How do I choose the right method to separate a mixture?

Choose the method from the property that differs between the components: filtration or settling for an insoluble solid in a liquid, evaporation for a dissolved solid, a separating funnel for immiscible liquids, distillation for different boiling points and sieving for different sizes. A mixture of many substances needs several of these methods in a sensible order.

What is the difference between decanting and filtration?

Decanting pours off the clear liquid after a solid has settled, whereas filtration passes the mixture through filter paper that holds the solid back. Decanting is quick but leaves some liquid with the solid and misses very fine suspended particles, while filtration holds back finer particles and gives a cleaner liquid but takes longer.

Why does alum clear muddy water?

Alum clears muddy water because its Al³⁺ ions neutralise the like charges that keep fine clay particles apart, so they clump into heavy flocs that settle and the clear water can be poured off. The dose matters, since too much alum leaves the particles suspended again, and the water still needs filtering and disinfecting before drinking.

Teaching ideas

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