Ch 5 Separation of substances

Ch 5 Separation of substances

Science

Methods of separation

• Handpicking

• Threshing

• Winnowing

• Sieving

• Sedimentation and Decantation

• Filtration

• Evaporation

Course

• Key terms ( Slide 4-10)

• Question / Answers ( Slide 11-13 )

• Fill in the blanks ( Slide 14-16 )

Handpicking

The simple process of separating slightly bigger sized harmful substances or other useful substances or impurities like small pieces of stones, husk, dirt from grains of wheat, pulses and rice is called handpicking.

Threshing

It is a process of loosening the edible of cereal, gram, paddy etc from the scaly inedible chaft that surrounds it. In this process stocks are beaten to free the grain seeds. Sometimes threshing can be done with the help of bullock or machines.

Winnowing

It is the process by which we can separate any heavy material from a lighter one with the help of wind or by blowing air

For example- Separation of husk from grains i.e. rice, wheat, etc with the help of wind. In the mixture of of husk and grains. Husk particles are comparatively lighter than grains 

Sieving

Sieving is a very simple convenient and time saving process through particles of varying sizes can be separated from each other with the help of a sieve. A sieve is nothing but a simple device with small pores in it which allows finer material like flour to pass, leaving behind any impurities it might contain.

Sedimentation and Decantation

Sedimentation is the process through which dirt and heavier particles of a mixture settle at the bottom when water is added to it. When dirt and dust particles have settled, the clear which forms the upper layer is moved to another container and the dirt and dust is done away with. 

Filtration

Filtration is the process through which dirt etc are separated from a solution by making the solution pass through the filter paper.

Evaporation

Evaporation is the process of converting a liquid into gas or vapour by increasing the temperature or pressure of the liquid. This process is often used to separate salt from water.

Q1 How will you separate sand and water from their mixture  

Ans To separate sand and water we will use process of filtration.

Q2 How will you separate sugar mixed with wheat flour 

Ans We will the process of sieving to separate the mixture.

Q3 how will you obtain clear water from a sample of muddy water

Ans We will obtain clear water with process of sedimentation and decantation, Filtration

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