Explain briefly how gases can be liquefied

Gases can be liquefied by cooling them to lower temperatures and applying high pressure, which brings the gas molecules closer together to form a liquid. Gases are made of particles that are far apart and move freely. Because of this, gases normally do not have a fixed shape or volume. To convert a gas into a liquid, we need to decrease the distance between its particles and reduce their energy.

Methods of Liquefying Gases

1. Cooling: By reducing temperature, the kinetic energy of gas particles decreases. As a result, they slow down and come closer, forming a liquid.
2. Applying Pressure: High pressure forces the particles to move closer, making it easier for them to condense into liquid form.
3. Combined Effect: In industries, both cooling and compression are used together to liquefy gases like oxygen, nitrogen, and carbon dioxide.

Examples

• Oxygen and nitrogen are liquefied and stored in cylinders for use in hospitals and industries.
• LPG (liquefied petroleum gas) is a gas that is stored under pressure as a liquid.

Applications of Liquefied Gases

• Medical use (liquid oxygen for breathing support).
• Cooking fuel (LPG).
• Industrial uses in welding and cooling systems.