Page 60 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

in a gas jar. Keep another gas jar on top of it in inverted
position (Figure 4.6).
Observe the colour of vapour.

What change occurs in the colour of iodine vapours
in the lower gas jar?

What about the upper gas jar?

What is the reason for this?

An incense stick has fragrance. But the fragrance fills the room Fig. 4.6
only when the stick is lit. Why do the fragrance spreads quickly
in the room when the incense stick is lit?

Is there any relation between temperature and diffusion? Why
does the smell of hot food spread quickly to a long distance?
Is the rates of diffusion of substances in gas and liquid the same?

Take water in a beaker, and add carefully a drop of red ink into
it.
What do you see? Does the ink spread in the water?
Compare the diffusion of iodine vapour and ink and find the
difference.

What is the relation between diffusion and movements of
particles in different states?
In solids, is there a similar possibility for diffusion?
Place a drop of ink on a glass plate and observe.

Diffusion is the spontaneous mixing of different particles
having freedom of movement

Find more examples for diffusion from daily life.

Spreading of the smell of fruits.

Pure Substances and Mixtures

You are now familiar with the states of matter and the properties

Basic Science VIII 59 59
Basic Science VIII