Pressure

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

Effect of Pressure on Gas.gif

Effect of change in pressure in matter - Teachoo.png

Increase in Pressure

When pressure is applied on gas , it converts into liquid

Example

  • 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

Example

  • 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

 

  1. Class 9
  2. Chapter 1 Class 9 - Matter In Our Surroundings (Deleted)

About the Author

CA Maninder Singh's photo - Founder at Teachoo
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo