Can matter change its state?
Effect of change of temperature:-
On increasing the temperature of solids, the kinetic energy of the particles increases in kinetic energy, the particles start vibrating with greater speed. The energy supplied by heat overcomes the forces of attraction between the particles. The particles leave their fixed positions and start moving more freely. A stage is reached when the solids melts and is converted to a liquid. The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.
*The melting point of a solid is an indication of the strength of the force of attraction between its particles.
*The process of melting, that is change of solid state into liquid state is also known as fusion. The melting point of ice is 273.15K or 0 o C.
*Latent Heat-The hidden heat which breaks the force of attraction between the molecules is known as the latent heat. Since the heat energy is hidden in the bulk of the matter is called latent heat.
*The temperature at which a liquid start boiling at atmospheric pressure is called its boiling.
*Boiling is a bulk phenomenon particles from the bulk of the liquid gain energy to change into the gaseous state. for ex- boiling point of water is 100 o C.{or 100oC=273+100=373K}
*Latent heat of vaporisation : The heat energy required to convert 1 kilogram of liquid into gas, at atmospheric pressure, at its boiling point is known as the latent heat of vaporisation.
There are some that change directly from solid state to gaseous state and vice versa without changing into liquid state.
- Sublimation: A change of state directly from solid to gas without changing into liquid state is called Sublimation.
- Deposition: The direct change of gas to solid without changing into liquid is called Deposition.
Effect of change of pressure
*Solid carbon dioxide is also known as dry ice because solid CO2 gets converted directly into gaseous state on decrease of pressure to 1 atmosphere.
