Separation of Mixtures – Lesson Summary

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Learning Objective

In this lesson we will learn how mixtures can be separated by a variety of methods, depending on the type of mixture and the physical properties of the component substances.

Learning Outcomes

By the end of this lesson you will be able to:

  • Describe the following separation methods, with examples: decanting, sieving, filtration, separating funnel, centrifugation, magnetic separation, evaporation, distillation and chromatography.
  • Define and identify: filtrate and residue, distillate, sediment and supernatant, mobile phase and stationary phase.
  • Draw and label diagrams of the different separation methods.
  • Determine the best method for separating common types of mixtures.

 
separation of mixtures lesson contents

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Lesson Topics

1 | Formation and Separation of Mixtures

2 | Principles of Mixture Separation

3 | Decanting

4 | Sieving

5 | Filtration

6 | Separating Funnel

7 | Centrifugation

8 | Magnetic Separation

9 | Evaporation

10 | Distillation

11 | Chromatography

12 | Summary

Lesson Summary

  • Since mixtures are formed by the physical combining of substances, they can also be physically separated.
  • The most appropriate technique for separating a mixture depends on the type of mixture and the physical properties of the components.
  • Separation techniques take advantage of differing physical properties between the components of a mixture, such as: melting and boiling point, size of fragments, solubility, density, magnetism and other forms of attraction.
  • Separation techniques can be divided into those that involve the separation of heterogeneous mixtures and those that involve the separation of homogeneous mixtures.
  • Decanting involves separating a liquid (supernatant) from a solid (sediment) by gently pouring off the liquid.
  • Sieving involves separating a mixture based on different sizes of components, where smaller fragments pass through holes in the sieve but large fragments do not.
  • Filtration is a special form of sieving where filter paper is used to trap very fine solid particles (residue) from the rest of a liquid or gas mixture (filtrate).
  • Separating funnels or used for separating liquids with different densities.
  • Centrifugation separates heterogeneous mixtures by spinning them at very high speeds, which forces components to separate into layers.
  • Magnetism can be used for separating magnetic materials from non-magnetic materials.
  • Evaporation is used for recovering dissolved substances from solutions by evaporating the solvent and crystallising the solute.
  • Distillation involves the evaporation of a liquid (distillate), which is then cooled and condensed back into a liquid, to be collected separately.
  • Chromatography separates mixtures based on their differing levels of attraction to two different substances, known as the mobile phase and the stationary phase.

 
laboratory distillation set-up

(Image: Simon, Pixabay)

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