Difference between Gas and Vapour

Gas and vapour are both forms of matter that exist in the gaseous state. However, there are distinct differences between the two. In this article, we will explore these differences in detail.




Definition

Gas: Gas is a state of matter in which the particles are widely spaced and move freely. It has no definite shape or volume and tends to expand to fill the container it is placed in.

Vapour: Vapour is the gaseous state of a substance that is normally a liquid or solid at room temperature and pressure. It is formed when the substance evaporates or sublimes.




Formation

Gas: Gases are typically formed when a substance reaches its boiling point or when a solid or liquid undergoes a physical or chemical change. For example, when water is heated, it boils and turns into steam, which is a gas.

Vapour: Vapour is formed when a substance evaporates or sublimes. Evaporation occurs when a liquid changes into a gas at a temperature below its boiling point. Sublimation happens when a solid directly transforms into a gas without becoming a liquid first.




State of Matter

Gas: Gas exists in the gaseous state at normal room temperature and pressure. It does not condense into a liquid or solid phase under normal conditions.

Vapour: Vapour is the gaseous state of a substance that is typically a liquid or solid at room temperature and pressure. It can condense back into its liquid or solid form when the temperature or pressure changes.




Examples

Gas: Examples of gases include oxygen, nitrogen, hydrogen, helium, and carbon dioxide. These substances exist as gases at room temperature and pressure.

Vapour: Examples of vapours include water vapour, steam, and gasoline vapour. These substances are normally liquids at room temperature but can exist in the gaseous state under certain conditions.




Visibility

Gas: Gases are generally invisible to the naked eye. They do not scatter or reflect visible light, which makes them difficult to observe directly.

Vapour: Vapours are often visible as they contain tiny droplets of the substance in the gaseous state. For example, steam is visible when water is boiled.




Conclusion

In summary, the main difference between gas and vapour lies in their formation and the state of matter they represent. Gases are substances that exist in the gaseous state at normal conditions, while vapours are the gaseous form of substances that are typically liquids or solids at room temperature and pressure. Gases are generally invisible, whereas vapours may be visible due to the presence of tiny droplets. Understanding these distinctions can help clarify the nature and behavior of these two forms of matter.