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CBSEEnglish Medium Class 9
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पाठ्यक्रम

Mixture

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Topics

  • Introduction
  • Separation of Unwanted Substances from Mixtures
  • Activity

Introduction:

Mixtures are formed when two or more substances are mixed together without participating in a chemical change. A mixture has a variable composition. A mixture shows the properties of the constituent substances. Physical methods can easily separate the constituents.

  • Atoms/molecules of a mixture are of two or more types.
  • The constituent molecules of a mixture are different from each other and are not joined by chemical bonds.
  • Components in a mixture retain their original properties because they are not chemically combined.
  • The proportion of constituent substances in a mixture can change.
  • The properties of constituent substances are retained in the mixture. 
  • Unlike compounds, mixtures do not have a fixed ratio of their components.

For Examples,

Air is a mixture containing nitrogen (N₂), oxygen (O₂), and other gases.


Types of mixture

  1. Homogeneous Mixtures: Homo means same. A homogeneous mixture is a mixture in which the composition is uniform throughout the mixture. For example, salt in water. It has a uniform composition, and it can’t be separated out physically.
  2. Heterogeneous Mixture: Hetero means different. A heterogeneous mixture is a mixture in which the composition is not uniform throughout the mixture. For example, vegetable soup. It has a non-uniform composition and can be separated out physically.

Separation of Unwanted Substances from Mixtures:

When unwanted substances are mixed into food or other materials, called adulteration, they make the mixture unsafe or unusable. To make it useful again, we can separate these unwanted components using simple methods.

Separation Method

Working

Example
Straining (Filtering) Separates solid particles from liquids Filtering tea leaves from tea
Sifting Separates fine particles from coarse ones Sifting flour to remove lumps or impurities
Picking Manually removes large unwanted items Picking stones from rice or pulses
Sorting Separates different types of items by hand Sorting good and rotten vegetables
Winnowing Separates lighter particles from heavier ones Separating husk from grains using air
Magnet Removes magnetic materials from mixtures Removing iron nails or filings from sand
Sublimation Separates substances that can change directly from solid to gas Separating camphor from a mixture

Example

List the points of differences between homogeneous and heterogeneous mixtures with examples.

Differentiate between homogeneous and heterogeneous mixtures with examples.

Sr. No. Homogeneous mixture Heterogeneous mixture
1. All the components of the mixture are uniformly mixed. All the components of the mixture are not thoroughly mixed.
2. No separation boundaries are visible. Separation boundaries are visible.
3. It consists of a single phase. It consists of two or more phases.
4. Example: Sugar dissolved in water. Examples: Air, sand and common salt.
5. The ingredients cannot be separated easily. Mixtures are easier to place because there are separation boundaries between the materials present.

Activity

To understand that mixtures are formed without chemical changes and how different methods can separate unwanted components.

  • Prepare sherbet by mixing water, sugar, lemon juice, and salt. Stir until the sugar dissolves.
  • Prepare Bhel by mixing puffed rice, onions, tomatoes, coriander, spices, and sev in a bowl.

Observe:

  • In sherbet, the sugar dissolves, but no new substance forms—it remains a mixture.
  • In bhel, all ingredients stay separate and visible, showing that they do not chemically combine.

Conclusion:

Mixtures can be formed without a chemical change. The components of a mixture can be separated using simple methods like straining, sieving, or picking out ingredients. This shows that mixtures are different from chemical compounds, as their components retain their original properties.

If you would like to contribute notes or other learning material, please submit them using the button below.

Shaalaa.com | Homogeneous mixture and Heterogeneous mixture

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