Change of State of Matter

Particles of Matter in Solid State

Arrangement:
Particles are arranged in an orderly manner and close to one another.

Movement:
Particles vibrate at fixed positions.

Forces:
very strong

Particles of Matter in Liquid State

Arrangement:
Particles are not arranged in order.

Movement:
Particles move randomly and slowly and sometimes will collide against each other.

Forces:
Strong but weaker than in the solid state.

Particles of Matter in Gaseous State

Arrangement:
The space between particles is moderately large. The particles are very far apart and randomly arrange.

Movement:
The particles move randomly in all directions at great speed.

Forces:
very weak.

Melting

Melting is the process where a solid changes to its liquid state at a certain temperature (called the melting point) and pressure when it is heated.

Freezing

Freezing is the process where a liquid changes to its solid state at a certain temperature (called freezing point) and pressure when it is cooled.

Vaporisation

Vaporization, is the process whereby atoms or molecules in a liquid state gain sufficient energy to enter the gaseous state.

Evaporation

Evaporation is the process where a liquid changes to its gaseous state below its boiling point.

Boiling is the process where a liquid changes to its gaseous state below at boiling point.

Factors that Affect the Rate of Evaporation

• Humidity of the air.
• Temperature of the substance.
• Flow rate of air.
• Inter-molecular forces.

Condensation

Condensation is the process by which a gas or vapor changes to liquid state at certain temperature and pressure when it is cooled.

Sublimation

Sublimation is a process of conversion of a substance from the solid to the vapour state without its becoming liquid.

Boiling Point

Boiling Point is the temperature at which the pressure exerted by the surroundings upon a liquid is equalled by the pressure exerted by the vapour of the liquid. Under this condition, addition of heat results in the transformation of the liquid into its vapour without raising the temperature.

Freezing Point

Freezing Point Freezing Point is the temperature at which a liquid becomes a solid.

Melting Point

Melting Point Melting Point is the temperature at which the solid and liquid forms of a pure substance can exist in equilibrium.

Graph of Heating

B-C:
The temperature remains constant because the heat that supplied to the solid is used to overcome the forces of attraction that hold the particles together. The constant temperature is called the melting point.

D-E:
The temperature remains unchanged. This is because the heat energy absorbed is used to overcome the intermolecular forces between the particles of the liquid rather than increase the temperature of the liquid. This constant temperature is the boiling point.

Melting Point

Q-R:
The temperature remains unchanged. This is because the energy produced during the formation of bonds is equal to the heat energy released to the surroundings during cooling. This constant temperature is the condensation point.

S-T:
The temperature remains constant until all the liquid changes to solid. This is because the amount of energy released is eaul to the amount of energy lost to the surroundings during cooling. This constant temperature is the freezing point.

Supercooling

Super-cooling is the cooling of a liquid to below its freezing point but keeping it in liquid state.