Change of State of Matter

1.Effect of Change of Temperature:

Solid to liquid: On increasing the temperature of solids, the kinetic energy of the particles increases which overcomes the forces of attraction between the particles thereby solid gets converted to a liquid.

Melting: Change of solid state of a substance into liquid is called melting.

Melting point: The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.

Melting point of ice is 0°c.

Liquid to gas: On heating a liquid like water, the kinetic energy of its particles increases as high as in a gas, thus causing the liquid to change to a gas.

Boiling: The change of a liquid substance into gas on heating is called boiling.

Boiling point: The temperature at which a liquid boils and changes rapidly into a gas at the atmospheric pressure is called its boiling point.

Boiling point if water is 100°C.

Gas to liquid: On cooling a gas like steam (or water vapour), the kinetic energy of its particles is lowered down, causing them to move slowly and bringing them closer, forming a liquid.

Condensation: The process, in which a gas, on cooling, turns into a liquid at a specific temperature is called condensation or liquefaction.

Liquid to solid:

When a liquid is cooled down by lowering its temperature, its particles lose the kinetic energy and come to a stationary position, causing the liquid to turn to solid.

Freezing: The change of a liquid substance into solid by lowering its temperature is called freezing.

Freezing point: The temperature at which the state of a substance changes from a liquid to a solid is called the freezing point of that substance.

Fusion: The process of melting, that is, change of solid state into liquid state is also known as fusion.

Latent heat: The heat energy that is required to change the state of a substance without causing any ruse in the temperature of the substance is called latent heat. Since, the heat energy is hidden in the bulk of the matter, it is called latent heat.

Latent heat of fusion: The heat energy required to convert 1 kilogram of a solid into liquid at atmospheric pressure, at its melting point, is known as the latent heat of fusion.

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.

Water vapour at 373 K have more energy than water at the same temperature because particles in steam have absorbed extra energy in the form of latent heat of vaporisation.

Sublimation: The change of state of a substance directly from a solid to gas or gas to solid, without changing into the liquid state, is called sublimation.

Can Matter Change its State?

We all know from our observation that water can exist in three states of matter–
• solid, as ice,
• liquid, as the familiar water, and
• gas, as water vapour.
What happens inside the matter during this change of state? What happens to the particles of matter during the change of states? How does this change of state take place? We need answers to these questions, isn’t it?

Pressure creates no effect on solids or liquids because both these states of matter are non-compressible. But if pressure is increased on solid it breaks.

But on the other hand application of pressure with reduced temperature can liquefy gases. For instance, during parties or stage shows you must have noticed smoke that spreads al around the stage. It is nothing but dry ice (solid carbon-dioxide). Solid carbon-dioxide is stored under high pressure that liquefies instantly as soon as the pressure is reduced to 1 atmospheric pressure.

• Effect of Change of Temperature on the State of Matter:

1. Change of State
2. Chemical Change
3. Expansion

• Effect of Change in Pressure on the State of Matter: