Chapter 9: Methods of Separation in Everyday Life
Picking stones from rice, sieving flour, filtering tea, making salt from seawater: we separate mixtures every day. In this chapter we learn the methods, why each one works, and how to choose the right one.
In this chapter you will
- explain why we separate mixtures
- use handpicking, threshing, winnowing and sieving
- use sedimentation, decantation, filtration and evaporation
- choose a method based on the properties of the parts
Topics
- Handpicking, Threshing and Winnowing NCERT Ch 9
Handpicking removes a few large or different-looking pieces.
- Sieving NCERT Ch 9
Sieving separates particles of different sizes using a sieve.
- Sedimentation, Decantation and Filtration NCERT Ch 9
Sedimentation: heavy insoluble particles settle. Decantation: pour off the liquid above.
- Evaporation and Condensation NCERT Ch 9
Evaporation separates a dissolved solid (like salt) from a liquid.
- Churning and Magnetic Separation NCERT Ch 9
Churning separates butter from curd; a magnet separates iron from a mixture.
Key words
- Mixture
- two or more things mixed together
- Threshing / winnowing
- loosening grain from stalks / separating husk with wind
- Sieving
- separating by size using a sieve
- Sedimentation / decantation
- letting solids settle / pouring off the liquid
- Filtration
- separating insoluble particles with a filter
- Evaporation / condensation
- liquid → vapour / vapour → liquid
Summary
- We separate mixtures to remove unwanted parts or to get useful ones.
- Handpicking, threshing, winnowing and sieving separate solids from solids.
- Sedimentation, decantation and filtration separate insoluble solids from liquids; evaporation separates dissolved solids.
- Churning and magnets are used too; often several methods are combined.