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The Kinetic Theory Of Matter
this is a model that helps us imagine how the matter is arranged and how it behaves and how this arrangement relates to the properties of the three states of mattermain point of the theory are
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All matter is made up of very tiny particles , which can not be seen by the naked eye.
Different substances are available as different types of particles (atoms , molecules or ions).
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The Particles move all the time
the higher the temperature the faster they move on average
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Heavier particles move more slowly than lighter ones at a ny given termeprature
Brownian Motion :
Show an understanding of the random motion of particles in a suspension (Known as Brownian motion) as evidence of the kinetic particle model of matter
As per kinetic theory
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All matter is made up of very tiny particles , which can not be seen by the naked eye.
Particles in Gases move randomly and they collide with each other . This motion can not be seen even by microscope , but any small substance that will be placed in the liquids and gases like pollen grain will be bombarded by the randomly moving particles and so they themselves will also move .
The movement of the small particles can be seen under microscope and this movement is an evidence for the kinetic model of matter (As it shows there are individual particles that make up solids liquids and gases)
The scientist Robert Brown observed in the year 1827 rapid random movement of pollen grains within water ,he could not explain this but later Einstein showed that there are separate particles within the water that were moving randomly and caused the grain to move.
You can see in the picture above how the yellow sphere is moving due to being bombarded by the fast random moving particles.
Brownian Motion 1
Dust particles in beam of light can be seen if magnified as moving randomly
Brownian Motion 2
Actually this random movement of the dust particles is because of being bombarded by the air particles moving randomly in all directions around it
Brownian Motion 3
This random motion is called the Brownian motion and is an evidence for the presence of particles as a making units for all Matter
Brownian Motion 1
Dust particles in beam of light can be seen if magnified as moving randomly
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Brownian Motion
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Scientist Robert Brown
Brownian motion of pollen grains in water
So now you can define
Brownian motion
as
Brownian motion is the random movement of particles in a fluid due to their collisions with other atoms or molecules.
Diffusion
is the movement of particles from an area of high concentration to an area of low concentration.
For this to occur the particles must be able to move so this occurs only in gases liquids and does not occur in solids because particles have no gaps in between them enough for the diffusion to occur.
What causes diffusion?
In gases and liquids, particles move randomly from place to place. The particles collide with each other or with their container. This makes them change direction.
Eventually, the particles are spread through the whole container.
Diffusion happens on its own, without stirring, shaking.
Examples for Diffusion
Solid particles Diffusing in Liquid particles
When small solid pieces of solid iodine or potassium manganate(VII) are dissolved in water
the solid particles diffuse in between the water particles and cause the solution
to be colored with the iodine color
Solid particles of Iodine Diffusing in-between water particles
Examples for Diffusion
Solid particles Diffusing in Gas particles
When you are throwing some small stones in the air , the solid particles of stones
diffuses in between the air gas particles
Examples for Diffusion
Gas particles Diffusing in Liquid particles
The particles of Carbon dioxide gas diffusing in water of a Carbonated drink is
a perfected example.
Examples for Diffusion
Gas particles Diffusing in another Gas particles
An example is the diffusion of bromine gas or Nitrogen Dioxide gas particles through air particles
Examples for Diffusion
Liquid particles Diffusing in Gas particles
Drops in rain falling in between air particles
Examples for Diffusion
Liquid particles Diffusing in another liquid particles
that what happens when you mix 2 liquids together
The rate of diffusion of gases
Gases diffuse because the particles collide with other particles, and bounce off in all directions
Note that gases do not all diffuse at the same rate.
The speed with which the gases diffuse depends on these two factors:
1 The mass of the particles
The particles in hydrogen chloride gas are twice as heavy as those in ammonia gas.
Cotton wool soaked in ammonia solution is put into one end of a long tube
(at A below). It gives off ammonia gas.
At the same time, cotton wool soaked in hydrochloric acid is put into the other end of the tube (at B). It gives off hydrogen chloride gas.
HCl and NH3 gases placed in wool cotton on both sides of the tube
The lower the mass of its particles, the faster a gas will diffuse.
When particles collide and bounce away, the lighter particles will bounce further. The particles in the two gases above are molecules.
The mass of a molecule is called its relative molecular mass.
So The lower its relative molecular mass, the faster a gas will diffuse.
Ammonium chloride formed as white smoke closer to HCl gas
The gases diffuse along the tube. White smoke forms where they meet: The white smoke forms closer to B. So the ammonia particles have travelled further than the hydrogen chloride particles – which means they have travelled faster.
2 The temperature
When a gas is heated its particles take in heat energy, and move faster. They collide with more energy, and bounce further away. So the gas diffuses faster. The higher the temperature, the faster a gas will diffuse.
Comparison of particles movement upon change of temperature
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