ACKNOWLEDGEMENT:
Figure
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Source of Figure
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Figure 6
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en.wikipedia.org
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Figure 7
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www.sciencephoto.com
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Diffusion:
Diffusion is the process by which
the particles move from a region of higher concentration to region of lower
concentration till equilibrium is achieved. It is a spontaneous mixing of
particles.
Examples from everyday life:
i. Drops of ink when added to a glass of water,
start swirling in the water body and start to mix with the water molecules
until the colour of the entire glass of water ink mixture becomes uniformly
blue in colour.
Figure 6:
ii. The smell/aroma of perfume or food spread
uniformly in the surroundings.
iii. Lab test:
Diffusion is tested in lab using 2 gas jars, one
inverted on top of the other, separated by a glass disc. One contains
brown/orange coloured Bromine gas while the other contains transparent air.
Figure 7:
Figure 7 shows the arrangement. The glass disc
separating the 2 jars is removed and the arrangement is left to stand. Soon,
the orange/brown Bromine mixes with the colourless air according to the
phenomenon of diffusion and the mixing continues till the colour of both the
jars becomes uniformly light orange/brown.
Diffusion is the evidence that
matter is made up of particles that can move from one place to another in their
liquid and gaseous states.
Rate of Diffusion:
The rate of diffusion is defined
as the speed at which the process of diffusion takes place. This rate depends
on 2 factors:
i.
Molecular/Atomic Mass of the diffusing
compound/element
ii.
Temperature
Molecular/Atomic Mass of the diffusing compound/element:
The heavier the molecule or atom,
the harder it is for it to move. Thus, it will take more time to diffuse.
Heavier the particle = Slower the rate of diffusion
Lighter
the particle = Faster the rate of diffusion
Temperature:
As temperature increases, the K.E
of the particles increases, this means that they can move with greater
velocities and hence diffuse more quickly. Temperature directly affects the
rate of diffusion.
High temperature = Faster diffusion
Low temperature = Slower diffusion
