Question

The number of phases of a mixture of four gases enclosed in a container are (a) 4 (b) 3 (c) 1 (d) 0

Short answer

The correct answer is (c) 1. The mixture of any gases is considered as a single phase.

Step-by-step solution

Understanding phases

In matter, a phase is defined as unique physical and chemical properties. Whenever several types of gases are mixed together in a container, they distribute uniformly, creating a homogenous solution.

Applying phases to the mixture of gases

Regardless of the types or numbers of gases mixed together, once distributed, it forms a single phase as it becomes a homogenous and evenly distributed mixture.

Key concepts

Homogeneous Mixture

In chemistry, a homogeneous mixture is a combination of two or more substances that are evenly distributed throughout the mixture. This means that no matter where you sample the mixture, it has a consistent composition and characteristics.
This uniformity happens because the substances involved are equally mixed at the molecular level. For instance, when sugar dissolves in water, it spreads out evenly, creating a homogeneous solution.

Characteristics of a homogeneous mixture include:

• Uniform appearance and composition
• The individual components cannot be easily separated by physical methods like filtration
• Properties are consistent throughout the entire mixture

Whether it's solids, liquids, or gases mixing together, if they form one continuous phase, it’s homogeneous. A critical aspect of understanding homogeneous mixtures is knowing that the mixture behaves as a single phase, with the distinct identities of the components being unobservable.

Gaseous Mixtures

Gaseous mixtures are mixtures made up entirely of gases. When gases mix, they follow the principles of diffusion and kinetic energy, spreading out to fill the available space in a container.
Unlike solids and liquids, gases do not settle due to their high energy particles. These particles are constantly moving in random directions, which leads to rapid mixing. This ability makes it possible for different gases to form a uniform mixture quite easily.

Key properties of gaseous mixtures are:

• Gases mix completely and uniformly, leading to a homogeneous mixture.
• They retain the general properties of gases such as compressibility and expansibility.
• Individual gases in a mixture still follow their specific gas laws, like Boyle's or Charles's Laws, within the mixture as a whole.

In applications, understanding gaseous mixtures can help in areas like chemical reactions, environmental sciences, and even industries like pharmaceuticals or cooking.

Physical and Chemical Properties

The terms 'physical and chemical properties' refer to the characteristics that describe substances and their behaviors either alone or in mixture, like a phase in matter.
Physical properties are aspects that can be observed or measured without changing the substance’s identity. Examples include color, phase (solid, liquid, gas), density, melting point, and boiling point.
Chemical properties, on the other hand, pertain to a substance's ability to undergo chemical changes or reactions, forming new substances. These include reactivity with other chemicals, flammability, and oxidation states.

When considering mixtures and phases, here's how these properties play a role:

• Homogeneous mixtures often focus on physical uniformity, indicating a single phase irrespective of the components.
• Chemical properties are crucial in determining the stability and compatibility of the components within the mixture.

Understanding these properties aids in predicting how substances within a mixture will behave under different conditions, allowing chemists to manipulate and control outcomes effectively.