Question

Which of the following are observed properties of gases? (a) variable shape (b) expand uniformly (c) compress infinitely (d) mix with other gases

Short answer

Observed properties are (a) variable shape, (b) expand uniformly, and (d) mix with other gases.

Step-by-step solution

Understanding the Nature of Gases

Gases are known to fill the space of any container they are placed in. This property relates to their variable shape, which means that gases do not have a fixed shape and will take on the shape of their container. Therefore, option (a) is a correct observation.

Exploring Expansion

Gases are also characterized by their ability to expand freely and uniformly to fill the entire volume available to them. This explains why gases take up the entire space without any gaps, making option (b) a true property of gases.

Assessing Compressibility

The statement 'compress infinitely' suggests that gases can be compressed into any possible smaller volume without limit. While gases are indeed compressible, 'infinitely' is not accurate because it does not consider the point where gases can liquefy under high pressure. Therefore, option (c) is not an observed property of gases.

Investigating Mixing of Gases

One of the notable properties of gases is their ability to mix with other gases. Examples include air, which is a mixture of different gases. This characteristic supports option (d) as a true observation.

Key concepts

Variable Shape

Gases are intriguing substances due to their absence of a fixed shape. Unlike solids or liquids, gases assume the form of their containers. This property is called 'variable shape.' It arises because gas molecules are far apart and move freely.

• A gas in a round balloon will be circular in appearance.
• When in a rectangular box, it will occupy a rectangular shape.

This flexibility showcases the advantage of gases in various applications, as they can easily fill containers of different sizes and shapes.

Uniform Expansion

The unique character of gases also includes their ability to expand uniformly. This means when a gas is not confined, it spreads evenly throughout the space available, without leaving any gaps. Such expansion is due to the natural movement of gas molecules, which aim to occupy the maximum available volume.

• This behavior is evident in a room filled with a fragrance: it will quickly disperse until it's uniformly distributed.
• It is also why a small gas leak soon becomes noticeable over a wide area.

Uniform expansion is crucial in understanding how gases behave under different temperatures and pressures.

Molecular Mixing

Gas molecules display a remarkable capacity to mix with other gases effortlessly. This property, known as 'molecular mixing,' allows gases to form homogenous mixtures effortlessly. Unlike in liquids or solids, where mixing might require external forces, gases naturally intermingle.

• Air, for example, is a perfect illustration where oxygen, nitrogen, and carbon dioxide form a uniform mixture.
• This interaction occurs swiftly, ensuring rapid and thorough blending.

Molecular mixing is significant in various natural processes, such as respiration and combustion.

Compressibility of Gases

One of the distinct features of gases is their high compressibility. Unlike other states of matter, gases can be compressed to occupy less volume. This is achieved because of the large spaces between gas molecules, allowing them to be drawn closer under pressure.

• Air compressors, for example, take advantage of this property to reduce the volume of air.
• However, it should be noted that gases cannot be compressed infinitely. Under extreme pressure, they can transition into a liquid state.

Understanding the limits of gas compression is critical, especially in industrial applications where pressure levels are crucial.