STATES OF MATTER AND PHASE CHANGE PROCESSES

 SSTATES OF MATTER AND PHASE CHANGE PROCESSES

 Differentiate between the three states of matter

Solids  Liquids Gases
Have fixed volume
and fixed shape
Have fixed volume
But have variable shape
Variable volume
And variable shape

What are the various types of phase changes?
Five types of phase changes

Phase change    Name of Process Practical Application
Solid to liquid Melting Melting of ice, Gold, Silver and Cast Iron
Liquid to solid Freezing Freezing of water into ice, milk into milk powder
Liquid to gas   Evaporation Water into steam, liquid refrigerant into vapor refrigerant in a fridge/air conditioner/water cooler
Gas to liquid Condensation  Steam into water in the steam condenser, Vapor refrigerant to liquid refrigerant in the condenser of a fridge/air conditioner/water cooler
Solid to gas   Sublimation Dry ice changes directly to carbon dioxide gas
Gas to a solid Deposition  When carbon dioxide gas changes into dry ice
When a gas changes into a plasma Ionization  Neon lights created by an electric current
When plasma changes into a gas Recombination  Turn off the power to a neon light,  the ionized particles will return to the gas phase.

Phase Change Process

Matter is anything that has mass and occupies space. Matter exists as solids, liquids, gases, and plasma states. A solid is any matter which has a definite shape and volume.  A liquid is any matter which has a definite volume but no definite shape. A gas is any matter which does not have a fixed shape or volume. Plasma is matter which exists in the form of high energy charged particles.

A phase change process of  change of matter from one state to another state. Phase changes occur regularly in nature and can also be achieved otherwise. The change of  phase depends on  the pressure and temperature of the matter and its surroundings. Therefore, by controlling the pressure and temperatures, phase change can be make to take place.

Different types of phase changes

Phase change temperature depends on pressure. These increase with the increase of pressure and decrease with the decrease of pressure. For example, boiling point of water is 1000C at 1 atmospheric pressure. It becomes 120 and 1350C at 2 and 3 atmospheric pressures respectively. There are in all eight phase changes that can occur. These are the followings:

  • Freezing:  When a liquid changes into a solid at its freezing temperature.
  • Melting : when a solid changes directly into a liquid at its melting temperature.
  • Condensation: When a gas changes directly into a liquid at its condensation temperature.
  • Vaporization: When a liquid changes directly into a gas at its vaporization temperature.
  • Sublimation: When a solid changes directly into a gas.
  • Deposition: When a gas changes directly into a solid.
  • Ionization: When a gas changes to plasma.
  • Recombination: When plasma changes to gas.