Dr. Nova
Change of state happens when kinetic energy changes. More heat means molecules move faster.
Molecule
Boiling: It is a process in which a liquid starts to boil.
Dr. Nova
The temperature at which a liquid starts to boil is called its boiling point
Dr. Nova
At boiling point, vapour pressure becomes equal to atmospheric pressure.
Dr. Nova
Water boils at 100°C.
Molecule
Evaporation: It is a spontaneous process that happens at the surface of a liquid.
Dr. Nova
It is the conversion of liquid into vapour.
Dr. Nova
Evaporation increases with temperature.
Dr. Nova
It depends on wind speed, temperature, and humidity.
Molecule
Melting: When a solid is heated, its temperature rises until it reaches the melting point.
Dr. Nova
After reaching melting point, extra heat does not raise the temperature until the whole solid melts.
Dr. Nova
During melting, solid and liquid exist together.
Heat Energy
Fusion: When energy is added, particles vibrate more and break free due to weak binding forces.
Molecule
Fusion is the change of state from solid to liquid.
Dr. Nova
The heat supplied at melting point is called latent heat of fusion.
Molecule
Vaporization: It is a phase transition where liquid changes into gas at its boiling point.
Dr. Nova
Vaporization depends on atmospheric pressure because boiling point depends on pressure.
Dr. Nova
Boiling starts when vapour pressure equals external pressure.
Dr. Nova
During vaporization, temperature remains constant at the boiling point.
Molecule
Condensation: It is the change of state from gas to liquid.
Dr. Nova
Water vapour cools down and becomes tiny water droplets on leaves and windows.
Molecule
Sublimation: Some solids change directly into gas without becoming liquid.
Dr. Nova
Examples are iodine, camphor, and naphthalene.
Dr. Nova
When the gas cools, it changes back into solid called sublimate.
Molecule
Deposition: It is the change of state from gas to solid directly without passing through liquid state.
Dr. Nova
Water vapour loses kinetic energy when it touches a cold surface and forms solid frost.
Molecule
Freezing: It is the process in which a liquid changes into solid.
Dr. Nova
The temperature at which a liquid freezes under one atmospheric pressure is called normal freezing point.
Dr. Nova
During freezing, energy flows from water to air and molecules become arranged in an orderly pattern.
Dr. Nova
Water freezes at 0°C.
Dr. Nova
Melting and fusion: solid to liquid.
Evaporation and vaporization: liquid to gas.
Condensation: gas to liquid.
Freezing: liquid to solid.
Sublimation: solid to gas.
Deposition: gas to solid.
