Changing States of Matter and its Effect
Changing States of Matter and its Effect :
- Whenever there is a change in the state of matter, primarily, the distance between its particles, the energy of its particles and the position of the particles change.
1 Effect of Temperature :
- On being heated the kinetic energy of the particles increases. When solid is heated, the rate of vibration of its particles increases. The energy provided by the heat extends across the force of attraction between the particles. Because of this the particles leave their set location and start moving independently. A stage is reached when the solid melts and become liquid.
- The temperature at which the solid melts down to liquid is termed as the melting point of that substance. The melting point of ice is 273.16ºK. The process of melting i.e., conversion of solid into liquid state is also known as fusion.
- “The heat energy required to change one kilogram of a solid into liquid, at its melting point, under one atmosphere pressure, is known as the latent heat or enthalpy of fusion i.e. melting.”
- On being heated, the kinetic energy of liquid particles increase further resulting in the conversion to gaseous state. The temperature at which liquid changes to gas is known as its boiling point.
- “The heat energy required to convert one kilogram of liquid, at one atmosphere pressure, at its boiling point, into the vapour state, is known as the latent heat or enthalpy of vapourisation“.
2 Effect of Pressure :-
- When pressure is applied the gas particles come close together. When the distance between these particles decreases, gaseous state changes into to the liquid state. But this liquid cannot be solidified by applying immense pressure because the compressibility of liquid is very less .
Important Points :-
- 1. Water, Air, Stone – all are matter.
- 2. There are primarily three physical states of matter – solid, liquid and gas.
- 3. The information regarding atom was first of all given by Maharshi Kanad.
- 4. Atomism was given by John Dalton.
- 5. Molecules are formed by chemical combination of atoms in a definite proportion.
- 6. Matter is present in the form of element, compound and mixture.
- 7. There are two type of molecules – elemental and compounds.
- 8. Mixture is formed by combining matter in indeterminate or definite proportions.
- 9. Conversion of ice into water is a physical change while breaking of ice molecules into hydrogen (H2 ) and oxygen (O2 ) is a chemical change.
- 10. The matter can be purified by crystallisation, distillation, fractional distillation, differential extraction, filteration etc.
Important Questions-Answers
Q. 1 When did Maharshi Kanad provided information regarding atom?
(a) 500 BC
(b) 100 BC
(c) 460 BC
(d) 1808 AD
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Q. 2 The atomicity of oxygen in ozone is :
(a) 1
(b) 2
(c) 3
(d) 4
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Q. 3 Which of the following substance is not solid at room temperature ?
(a) Salt
(b) Alum
(c) Oxygen
(d) Sal ammoniac
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Q. 4 The temperature at which liquid changes to solid is known as :
(a) melting point
(b) boiling point
(c) freezing point
(d) condensation temperature
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Q. 5 Which of the following options, is a mixture?
(a) Water
(b) Brass
(c) Iron
(d) Salt
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