" AKC SCIENCE CLASSES"
CLASS 09 TH (CBSE AND MP BOARD)
"CHAPTER 01"
"MATTERS IN OUR SURROUNDING"
"BASIC CONCEPTS"
- Anything that occupies space and has mass and is felt by sense is called matter.
- According to indian ancient philosopher, matter is the form of five basic elements (the Panchtatva) - air, earth, fire, sky and water.
- Made up of tiny particles.
- Vacant spaces exist between particles.
- Particles are in continuous motion.
- Particles are held together by forces of attraction.
Basis of Classification of Types
- Based upon particle arrangement.
- Based upon energy of particles.
- Based upon distance between particles.
- Solid
- Liquid
- Gas
- Plasma
- Bose-Einstein Condensate (BEC)
- Fixed mass, volume and shape.
- Inter-particle distances are least.
- Incompressible.
- High density and do not diffuse.
- Inter particle forces of attraction are strongest.
- Constituent particles are very closely packed.
- Not fixed shape but fixed volume and mass.
- Inter particle distances are larger than solid.
- Almost incompressible.
- Density is lower than solids and can diffuse.
- Inter particle forces of attraction are weaker than solids.
- Constituent particles are less closely packed.
(Ⅲ) GAS
- Neither fixed shape nor fixed volume.
- Inter particle distances are largest.
- High compressible.
- Density is least and diffuse.
- Inter particle force of attraction are weakest.
- Constituent particles are free to move about.
(Ⅳ) PLASMA (NON-EVALUATIVE)
- A plasma is an ionized gas.
- A plasma is a very good conductor of electricity and is affected by magnetic fields.
- Plasma, like gases have an indefinite shape and an indefinite volume. Example:- Ionized gas
- A BEC is a state of matter that can arise at very low temperatures.
- The scientists who worked with the Bose-Einstein condensate received a Noble Prize for their work in 1995.
- The BEC is all about molecules that are really close to each other (even closer than atoms in a solid).
- Solids have a definite shape and a definite volume because volume because the particles are locked into place.
- Solids do not flow easily because the particles cannot move/slide past one another.
- Solids are not easily compressible because there is little free between particles.
- Liquid are not easily compressible and have a definite volume because there is little free space between particles.
- Liquids flow easily because the particles can move/slide past one another.
- Gases are easily compressible because there is a great deal of free space between particles.
- Gases flow very easily because the particles randomly move past one another.
- Gases have an indefinite shape and an indefinite volume because the particles can move past one another (non-evaluative)
- Plasmas have an indefinite shape and indefinite volume because the particles can move past one another.
- Plasmas are easily compressible because there is a great deal of free space between particles.
- Plasmas are good conductors of electricity & are affected by magnetic fields because they are composed of lens.
- Particles are less energetic than solids because exist at very low temperature.
- Particles are literally indistinguishable because they are locked into same space.
- BEC shows super fluidity because Particles can flow without friction.
Water can exits in three states of matter:-
- Solid, as ice,
- Liquid, as the familiar water, and
- Gas, as water vapour.
(a) Effect of change in temperature :-
The temperature effect on heating a solid varies depending on the nature of the solid & the conditions required in bringing the change.
- On increasing the temperature of solids, kinetic energy of the particles increases which overcomes the force of attraction between the particles thereby solid melts and is converted to a liquid.
- The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.
- The melting point of ice is 273.16 K.
- The process of melting, that is, change of solid state into liquid state is also known as fusion.
- Increasing or decreasing the pressure can change the state of matter. Appling pressure and reducing temperature can liquefy gases.
- Solid carbon dioxide is stored under high pressure. Solid carbon dioxide gets converted directly to gaseous state on decrease of pressure to 1 atmosphere without coming into liquid state. This is the reason that solid carbon dioxide is also known as dry ice.
3) LATENT HEAT :-
The hidden heat which breaks the force of attraction between the molecules during change of state.
FUSION :- Heat energy required to change 1kg of solid to liquid.
VAPORISATION :- Heat energy required to change 1kg of liquid to gas at atmospheric pressure at boiling point.
Thus, we can say that pressure and temperature determine the state of a substance, whether it will be solid, liquid or gas.
4) EVAPORATION & BOILING :-
- Particles of matters are always moving and are never at rest.
- At a given temperature in any gas, liquid or solid, there are particles with different amounts of kinetic energy.
- In the case of liquids, a small fraction of particles at the surface, having higher kinetic energy, is able to break away from the force of attraction of other particles and gets converted into vapour.
- This phenomenon of change of a liquid into vapours at any temperature below its boiling point is called evaporation.
- The rate of evaporation increases with an increases of surface area.
- With the increase of temperature, more number of particles gets enough kinetic energy to go into vapour state.
- Humidity is the amount of water vapour present in air. The air round us cannot hold more than a definite amount of water vapour at a given temperature. If the amount of water in air is already high, the rate of evaporation decreases.
- Wind speed :- The higher the wind speed, the more evaporation.
- The particles of liquid absorb energy from the surrounding to regain the energy lost during evaporation.
- Boiling is a bulk phenomenon. Particles from the bulk (whole) of the liquid change into vapour state.
- Evaporation is a surface phenomenon. Particles from the surface gain enough energy to overcome the force of attraction present in the liquid and change into the vapour state.
(5) KELVINE & CELSIUS SCALE :-
- Kelvin is the SI unit of temperature, 0℃ = 273.16K we take 0℃ = 273K.
- SI unit of temperature is Kelvin. T(K) = T(℃) + 273.
- Kelvin scale of temperature has always positive sign, hence regarded as better scale than Celsius.
- Atmosphere (atm) is a unit of measuring pressure exerted by a gas. The SI unit of pressure is Pascal (Pa).
- 1 atmosphere = 1.01 × (10 to the power 5) Pa. The pressure of air in atmosphere is called atmospheric pressure. The atmospheric pressure at sea level is 1 atmosphere, and is taken as the normal atmospheric pressure.
