Mixtures

Questions

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Mixtures

A mixture is a substance that consists of two or more elements or compounds not chemically combined together.

Examples:

• Air is a mixture of gases like oxygen, nitrogen, argon, carbon dioxide, etc.
• Gun Powder is a mixture of potassium nitrate, sulfur, and charcoal.
• Brass is a mixture of copper and zinc.

The various substances present in a mixture are called its constituents or components.

Types of mixtures:

1. Homogeneous Mixture
2. Heterogeneous Mixture

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Homogeneous Mixture

1. Those mixtures in which the substances are completely mixed together and are indistinguishable from one another.
2. They have a uniform composition throughout their mass.
3. They have no visible boundaries of separation between various constituents.
4. Examples: Sugar solution, salt solution, alcohol and water, soft drinks, etc.

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Heterogeneous Mixture

1. Those mixtures in which the substances remain separate and one substance is spread throughout the other.
2. They do not have a uniform composition.
3. They have visible boundaries.
4. Examples: Sugar and sand, salt and sand, milk, soil, blood, starch, muddy water, etc.

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Properties of Mixtures

1. They can be separated into their constituents by physical processes (filtration, evaporation, sublimation, distillation).
2. A mixture shows the properties of all its constituents present in it.
3. Formation of a mixture is a physical change, i.e., energy (in the form of heat, light, etc.) is usually neither given out nor absorbed in the preparation of a mixture.
4. The constituents are present in any proportion by mass.
5. They do not have definite melting and boiling points.
6. They can be homogeneous or heterogeneous.

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Difference Between Compounds and Mixtures

Mixtures	Compounds
1. A mixture can be separated into its constituents by physical processes.	1. A compound cannot be separated into its constituents by physical processes.
2. A mixture shows the properties of its constituents.	2. A compound does not show the properties of its constituents.
3. Energy is usually neither given out nor absorbed in the preparation of a mixture.	3. Energy is usually given out or absorbed during the preparation of a compound.
4. The composition of a mixture is variable; the constituents can be present in any proportion by mass.	4. The composition of a compound is fixed; the constituents are present in fixed proportions by mass.
5. A mixture does not have a fixed melting and boiling point.	5. A compound has a fixed melting and boiling point.