Physical nature of matter

Any substance which occupies space and has mass and the presence of which can be felt by any one or more of our five sense organs is called matter.

Example - book, pen, copy, air, water, etc.

Ancient Indian philosophers believed that all matter (living or non-living) was made up of five basic elements (panch-tatva) - Air (Vayu), Earth (Prithvi), Fire (Agni), Sky (Akash) and Water (Jal)

Diffusion is a process of movement of particles from the region of its higher concentration to the region of its lower concentration.

The zig zag movement of the small particles suspended in a liquid (or gases) is called brawnyn motion.

e.g., movement of pollen grains on the surface of water

Brawnyn motion increases on increasing the temperature.

The process of diffusion and Brawnyn motion gives two conclusions about the nature of matter-
  •  Matter is made up of tiny particles.
  •  Particles of matter are constantly moving.

The important characteristics of particles of matter (like atoms or molecules) are as follows -
a) The particles of matter are very very small.
b) The particles of matter have space between them.
c) The particles of matter are constantly moving.
d) The particles of matter attract each other.

Materials Required:
  •  Six glass beakers (100 ml capacity)
  •  A test tube
  •  Few crystals of potassium permanganate (KMnO4)

Procedure:
  •  A few crystals of potassium permanganate are taken in a beaker and dissolve in 100 ml of water.
  •  10 ml of this coloured solution is taken out with the help of a test tube and poured into another beaker, containing 90 ml of clear water.
  •  Again 10 ml of this coloured solution is taken out with the help of a test tube and poured into the third beaker, containing 90 ml of clear water.
  •  This process of dilution is repeated till the pink colour persists in the beaker.

Observation:
  •  Initially the colour of the solution is dark purple, which goes on fading at each dilution.
  •  After 7-8 dilution, the pink coloured solution is left and the colour is so fade that it is only just noticeable.

Inference:
  •  The particles of potassium permanganate gradually decrease in each dilution. Thus, the particles of matter are very very small and not visible to naked eyes.

Materials required:
  •  A glass beaker (100 ml)
  •  A spoon full of common salt
  •  A glass rod

Procedure:
  •  The glass beaker is half filled with water and the level of water is marked.
  •  The common salt is poured in the beaker and thoroughly stirs with glass rod.

Observation:
  •  The salt dissolve in water and disappears.

Inference:
  •  Salt is made up off very small, particles, which when dissolved in water break off from each solid granule and mix with water particles in the liquid. It also shows that the particles of water have enough space to dissolve salt particles in it.

Experiment I
  •  Aim: To study the moving nature of particles of matter.

Material Required –
  •  Incense sticks
  •  Match box Procedure –
  •  A few incense sticks are kept in one corner of a room lighted with the help of match stick.

Observation –
  •  Fragrance spread in the whole room very quickly.

Inference –
  •  The burning of incense sticks produce gases (or vapours) having pleasant smells. The particles of gases produced by the burning of incense sticks move rapidly in all directions and reach every part of the room quickly. When the gaseous particles from the incense sticks can reach our nose with air we can smell the fragrance. Hence the particles of matter are constantly moving.

Experiment – II
  •  Aim – To study the rate of diffusion of two different types of particles of matter

Materials required –
  •  Two beakers (100 ml capacity)
  •  Water
  •  Water soluble ink of any colour
  •  Honey

Procedure –
  •  The two beakers are taken and half filled with water.
  •  A drop of coloured ink (say red) is put in the first beaker and a drop of honey is put on the second beaker.
  •  The two beakers are left undisturbed for some time.

Observation –
  •  The drop of ink spreads immediately while it takes much time for honey to spread in water. The reason behind this observation is that particles of ink (matter) are more free to move around as compared to the particles of honey.

Inference –
  •  Both the particles of ink and honey as well as water are in constant motion which results in the evenly spreading of both ink and honey in water.

Experiment- III
  •  Aim – To study the effect of temperature on the rate of diffusion

Materials required –
  •  Crystals of copper sulphate
  •  Two beakers (each of 100ml capacity)

Procedure –
  •  A few crystals of copper sulphate are dropped into the first beaker containing hot water and into the second beaker containing cold water.
  •  The crystals are allowed to settle at the bottom without stirring the solution.

Observation –
  •  The particles of copper sulphate goes into the water and turn whole water blue.
  •  The particles spread slowly in cold water while much rapidly in hot water.

Inference –
  •  Both the particles of copper sulphate and water are in motion which results in the diffusion process and turns the water blue.
  •  The particles diffuse rapidly in hot water due to gain of more kinetic energy.

Example – I
  •  Let us take a piece of chalk, a cube of ice and an iron nail.
  •  All the three are bitten with hammer.
  •  It is seen that it is very easy to break the piece of chalk into smaller pieces, it requires more force to break a cube of ice, whereas an iron nail does not break at all even at a larger force.
  •  This shows that force of attraction between the particles of chalk is quiet weak; the force of attraction between the particles of ice is a bit stronger, whereas the force of attraction between the particles of iron nail is very strong.

Example - II
  •  We can move our hand through air very easily because the force of attraction between the particles of air (which is a gas) is very small or almost negligible.
  •  We can also move our hand through water in a bucket fairly easily because the force of attraction between the particles of water (which is a liquid) is also small.
  •  But we cannot move our hand through a plank of wood because the force of attraction between the particles of wood (which is solid) is very strong.
  •  Thus, the force of attraction is maximum in the particles of solid matter, less in liquid matter and minimum in the particles of gaseous matter.