Mixtures can be separated using the different properties of the materials. Sieving separates solids with different-sized pieces, like pebbles from sand. Filtering uses a filter paper to separate an insoluble solid, like sand, from a liquid, like water: the water passes through and the sand stays behind.
Evaporating separates a dissolved solid from a liquid. If salty water is left in a warm place, the water evaporates and the salt crystals are left. A magnet can pull iron filings out of a mixture with sand, because iron is magnetic and sand is not. Choosing the right method depends on the property that is different.
Worked example
How would you get the sand back from a mixture of sand and water?
- Sand does not dissolve, and its grains are bigger than the holes in filter paper.
- Pour the mixture through a filter paper in a funnel.
Answer:The water drips through and the sand is left on the paper.
Key words
- sieve
- a mesh that separates big pieces from small ones
- filter
- a paper or cloth that lets liquid through but traps solid bits
- evaporate
- heat or leave a solution so the liquid turns to gas
- insoluble
- does not dissolve
New questions every time.
NGSS-referenced: 5-PS1-3