Separating mixtures
Filtration, evaporation, distillation, chromatography and other ways to separate mixtures. Read one part at a time and tap “I know this”. Then test yourself in the quiz.
Know it already? Jump straight to the quiz
The methods
| Method | When | Example |
|---|---|---|
| Filtration | Insoluble solid from a liquid | Chalk dust from water |
| Evaporation | Get the dissolved solid back | Salt from salt water |
| Distillation | Get the liquid back | Water from salt water |
| Chromatography | Separate dyes | Colours in ink |
| Sieving | Different sizes | Pebbles from sand |
| Magnet | Magnetic substance | Iron nails from sand |
| Pouring off | Oil floats on water | Cooking oil from water |
Burning is not a physical separation method: it makes a new substance.
Filtration up close
Pour muddy water through a funnel with filter paper. The mud stays in the paper: that is the residue. The clear water that runs through is the filtrate. Water works first use screens that work like sieves to remove leaves and sticks.
Solutions
In a solution one substance dissolves fully in another. The solvent is what it dissolves in; the solute is what dissolves. Stir, and a solid dissolves faster. A suspension’s bits float, then settle. Industry uses separation to get pure substances from natural mixtures.
Remember this and test yourself
- Filtration separates an insoluble solid from a liquid: the residue stays behind, the filtrate passes through.
- Evaporation gets the salt back; distillation gets the water back (different boiling points).
- Chromatography separates the colours in ink.
- Sieve for different sizes; a magnet for iron (copper is not magnetic).
- Filtering cannot remove salt from water: dissolved salt passes through the paper.
Write these points in your book. Read them again the night before the test.
Want the salt? Evaporate. Want the water? Distil. Want the colours? Chromatography.
Important words
First say what the word means, then turn the card over.
Match column A to column B
Tap a word in column A, then its meaning in column B. You can also start in column B.
True or false?
Read the question and the answer. Is the answer right? Tap True or False.
Now the real quiz!
The quiz has many more questions on this topic. Every question shows straight away whether you are right and explains why.
Take the quiz: Separating mixtures- Read one part together and ask your child to tell it back in their own words.
- The ticks (“I know this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 7 Natural Sciences. Always check your teacher’s notes and textbook too.