Pressure may be defined as the physical force applied on an object.
The particles of matter come closer t o each other when pressure is applied
When pressure is applied on gas enclosed in a cylinder, it is converted to liquid (as the particles come closer)
However it is difficult to apply pressure on liquid and solids.
- The space between the particles in solids and liquids is already very less
- Applying pressure will not bring the particles closer and so will not bring a change in state of matter.
Thus, by applying pressure and cooling , gases can be converted to liquids.
Matter can change state because of Increase or Decrease in Pressure
Increase in Pressure
When pressure is applied on gas , it converts into liquid
- If we put some gas in a test tube and compress it with help of test tube it compresses (converts into liquid)
Decrease in Pressure
Due to decrease in pressure, solid can turn into gas
- Solid Carbon dioxide (also called dry ice) gets converted into gas at room temperature,
- This is due to the decrease of pressure to 1 atm (atmosphere)
What is 1 atmosphere?
The pressure of air in the atmosphere is called atmospheric pressure
The atmospheric pressure of air at sea level is taken to be 1 atmosphere
1 atmosphere = 1.01 × 10 5 pascal