Page 43 - ICSE Chemistry 6
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Let’s understand sedimenta on and decanta on by performing Ac vity 2.5.
Activity 2.5
Aim: To separate a mixture of sand and water by sedimenta on and decanta on
Materials required: 2 beakers, some sand, some water, a glass rod
Procedure 1
• Take a mixture of sand and water in a beaker.
• S r it and keep it undisturbed for 15–20 minutes.
Observa on 1: You will observe that sand se les down at the bo om of the
beaker, leaving clear water over it. This process is sedimenta on.
Procedure 2
• Now take another beaker
glass rod
and put a glass rod in it.
• Pour the water gently from mixture of sand clear water
fi rst beaker into the second and water (supernatant)
sand
beaker along the glass rod, (sediment)
as shown in the fi gure.
Observa on 2: You will observe that sand and water get separated. This process is decanta on.
Limitations of Sedimentation and Decantation
• The components of an insoluble solid and liquid cannot be completely separated.
• The components of a solid which is lighter than liquid do not se le down, hence, they cannot be
separated.
Filtration
This method is used to separate an insoluble solid and a liquid. In
this process, the mixture to be separated is passed through a fi lter
paper. The fi lter paper has ny pores that allows only the liquid
to pass through it and the insoluble solid par cles remain on the
fi lter paper. The insoluble solid le behind on the fi lter paper is
called residue and the clear liquid that passes through the fi lter
paper is called fi ltrate.
In addi on to the fi lter paper, we can also use glass wool, charcoal,
Fig. 2.8: Filtration
sand, unglazed porcelain, co on and strainer.
The technique of fi ltra on is daily used in our houses to separate tea leaves from tea using a strainer.
Filtra on is also used to remove pulp from fresh juice.
Thirst for Knowledge
Filter paper is a special kind of paper which has ny pores of specifi c dimension. It allows only liquid to
pass through, whereas undissolved solid par cles are retained on the fi lter paper.
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