Question

Which property of gases makes it possible to fill large volume of gases in small cylinders.

1. A spoonful of sugar is added to a beaker containing 500 ml of water and stirred for a while. State any two observations that you will make.

2. Suggest a method to liquefy atmospheric gases

Answer 1

• When a spoonful of sugar is added to a beaker containing 500 ml of water and is stirred for a while.
  

The following observations can be made:

1. We observe that sugar gets dissolved

2. Level of water after dissolving sugar is same as before adding sugar. That means there is no increase in its volume.

3. We can conclude that there as spaces between the particles of water and these spaces accommodate sugar particles.

4. Particles in water are not tightly packed. They have spaces in between them.

• The atmospheric gases exist as liquids at very low temperatures such as $-{150}^{0}C\text{to}-{200}^{0}C$. To liquefy such gases by cooling is practically very difficult. Only a few gases are cooled to liquefy them.
  

To liquefy a gas we need to bring the gas molecules together very close to each other. This is achieved by compressing them using high pressures. At very high pressures, the boiling point of the liquid rises. So at practically achievable temperatures, the gases can liquefy and exist as liquids.

This principle is used to liquefy oxygen, hydrogen, helium, nitrogen, and petroleum gas too. The LPG cylinder contains liquefied petroleum gas at high pressure.