METTER IN OUR SURROUNDING
Metter –Anything which occupies space and has mass is called matter.
In other words, anything which has mass and volume is called matter.
Ex- chair, table, computer, mouse, keyboard, dog, cat, cow, pencil, tree, plant building, mountain, river, etc.
According to their physical and chemical properties, matters can be divided into three group –
(1) Solid-ठोस
(2) Liquid-द्रव
(3) Gas-गैस
Properties of Matter – पदार्थ के गुण
* Matter is made up of small particles.
* These particles are very small in size.
* These particles have space between them.
* These particles have spaces between them.
* Particles of matter attract each other because of force attraction.
Experiments-
1. Experiment with Pollen Grains
* If we suspend extremely small pollen grains in water and see through microscope, we found that the tiny particles of water do collisions with pollen grains.
* Due to these collisions, pollen grains move slightly.
2. Mixing of Ink with Water
* If we put a drop of ink in water, we see that initially ink is present in small portion of water and after some time, ink spread up all over in the water.
* This happens because the tiny particles of water collide with tiny particles of ink. Due to these collisions, particles of water and ink with each other.
From above two experiments, it is proved that:
* Matter is made up of tiny particles.
* Particles do Brownian motion.
Brownian motion of Dust Particles and Smoke-
* Mr. Robert Brown, a Scottish botanist observed the random movement of pollen grains in water in 1827, this movement of particles is called Brownian motion.
* Dust moves randomly because the random moving particles of air collide with dust particles.
* Similarly, smoke also moves randomly because the random moving particles of air collide with smoke particles again and again.
Spreading of Smell –
* When we spread perfume, tiny particles of air collide with tiny particles of which is liquid. Due to these collisions, particles of perfume spread in the air. That’s why we feel the smell of perfume.
* Spreading ofsmell proves that matter is made up of tiny particles moving randomly.
Experiment with Sugar and Water-
* Take a beaker which is filled with water up to certain mark.
* Add some sugar in it
* We see that marking of water in a beaker increases.
* Keep stirring the solution. After some time sugar dissolved in water and level of the water comes down to original mark.
* This happens because the tiny particles of sugar adjust themselves in the space between the tiny particles of water.
This experiment proves that:
i. Matter is made up of tiny particles.
ii. There is a space between these particles.
Mixing Potassium Permanganate or Copper Sulphate with Water-
* Put a small crystal of potassium permanganate in a beaker filled with water.
* Stir the solution.
* You will see that crystals of potassium permanganate dissolve in water and colour of water becomes dark pink.
* Let’s take another beaker filled with water and put small amount of dark pink solution in it.
* We see that beaker in which only water is present becomes light pink; lighter than previous solution.
* Repeat this activity again. You will find the same result that water turns to pink but lighter than previous one.
* It means that even small amount of solution contains lots of particles of potassium permanganate.
* Or we can say that particles of potassium permanganate are too small that their small amount can change the colour of entire water as we saw in this experiment.
* Similarly, if we do the same experiment with copper sulphate then water becomes the blue.
This experiment proves that particles of matter are very small.
Diffusion-विसरण
* The process of mixing of two substance due to Brownian motion of particles is called Diffusion.
* As teprerature increase. Brownian motion increases and diffusion becomes fast.
* Diffusion takes place from higher concentration to lower concentration.
* It is a natural process.
* It takes place in solid, liquid and gases.
Three States of matter –
Solid, liquid and gas
Solid:- Solids have fixed volume and shape.
Ex- stone, wood, brick, ice, sugar, salt, coal, etc.
Properties of Solid
* In solids, particles are closely packed and they have very less spacing between them.
* In solids, particles only vibrate at their position and they have less kinetic energy.
* The force of attraction between the particles of solids is very strong.
Liquid: Liquids have fixed volume but indefinite shape.
Properties of Liquid
* In liquids, particles are less closely packed and they have very less spacing between them with respect of solid.
* In liquids there is a weaker force of attraction and more spacing between the particles.
* In liquids, particles can move around and have high kinetic energy. Example- milk, water, petrol, kerosene, alcohol, oil, etc.
Gas: Gases have indefinite shape and volume. Example-air, oxygen, hydrogen, nitrogen, carbon-dioxide, etc.
Properties of Gas
* In gas, particles are very loosly packed and they have very large space between them.
* In gas there is a very weak attraction and very large spacing and between particles.
* Particles of gases move around very easily and have very high kinetic energy.
Properties of States of Matter –
1. Filling Container-
* The force of attraction between the tiny particles in gases is very less.
* Due to this, these particles can easily move away from each other and thus filling the container.
* In solids and liquids, attraction force is sufficient enough for not letting the particles move away from each other.
2. Shape and Volume –
Shape: Due to less attraction force between particles, particles of liquid and gas can easily move around. Thus they can take any shape as per the container.
Volume: –Gases have so little attraction among particles that they can easily change spacing between themselves, so they can easily change their volume.
* In liquids, attraction force is large enough so that spacing between particles does not change easily, so liquid has fixed volume and same with solids.
* Solids can change shape on applying force. Liquids and gases do not need force to be applied for changing shape.
* Some solids have gas inside them. So they can be easily aqueezed to change to shape.
* Sponges have many small air filled holes, when we squeezed them, air from these holes can come out changing the shape of sponge.
3. Compressibility and Rigidity-संपीडयता और कठोरता
Compressibility: Spacing between particles of gases can be decreased so gases have high compressibility. But spacing between particles of solid or liquid cannot be decreased, so they cannot be compressed.
Applications of Compressed Gas-
* Compressed helium gas is filled in air balloons.
* Compressed natural gas (CNG) is filled in cylinders which are usedin vehicles.
* Liquefied petroleum gas (LPG) is filled in cylinders which are used for cooking.
Rigidity: It is property of a substance to resist any deformation like change in shape, being compressed etc. Solids have high rigidity, liquids have less rigidity and gases have no rigidity.
4. Moving Through- As we try to move through gases and liquids, their particles move away from our path creating space for us. So we can move through them. Particles of solids cannot move away from our path, so we cannot move though them.
5. Fluidity-द्रवता
* Fluids are substances which can flow.
* Liquids and gases have fluidity.
* But solids do not have fluidity.
6. Density-घनत्व
Density= Mass/Volume
Particles in solids are very closely packed so they have high density. In gases, there is plenty of space between particles due to which density is low.
7. Diffusion-प्रसार Diffusion is the process of mixing of different substances with each other due to random motion of their particles.
* If a bottle of perfume is opened in one corner of a room. It spreads in the whole room by diffusion.
* If we drop a little ink in a beaker of water, it will spread by itself in the beaker of water and the color spreads uniformly due to diffusion
Diffusion of Bromine in air-
A gas jar of bromine and a jar of air are placed, separated by a cover plate. The cover plate is removed so that the two open ends of the jars are in contact. The bromine gas spreads (diffuses) rapidly into the air to produce a uniform redish brown colour in both jars as we can see in fig. (b).
* Aquatic animals take oxygenand carbon dioxidefor their survival because of the diffusion phenomenon. Oxygen and carbon dioxide present in air diffuses in water and dissolves in it. Aquatic animals inside water can take these dissolved gases for their survival.
8. Pressure –
* Take a container filled with gas.
* The tiny particles of gas collide with walls of container while doing random motion.
* Due to this pressure is exerted on walls of container. If temperature of gas is high, particles move faster and exert more pressure on walls.
* Particles of liquid can also exert pressure as they can do random motion. As they can do random motion. As temperature increases, pressure increases.
Measurement of Temperature– Different units can be used to measure the temperature in different scales. Most known units of measurements are Kelvin and Degree Celsius.
Kelvin-
* Kelvin is the SI unit of temperature. The symbol of Kelvin is ‘k’.
* The scale of Kelvin is used widely because of its many advantages over degree Celsius. In Kelvin scale, temperatures are written in positive usually.
* 273 k is defined as the freezing or melting point of ice.
* 373k is defined as the boiling point of water.
* At Kelvin scale -273 k is considered as the absolute zero temperature.
Degree Celsius-
* Degree Celsius is written as 0C