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Mention the properties of colloids with the explain any two of them and also example of crystalloids and colloids

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properties of colloids Tyndall effect Brownian motion examples crystalloids colloids chemistry

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Properties of colloids

Colloids are mixtures in which particles of the dispersed substance are intermediate in size between those in a true solution and a suspension. They generally have particle sizes of about 1 to 1000 nm.
  1. Heterogeneous nature
    A colloid has two phases:
    • Dispersed phase: the particles present in small amount
    • Dispersion medium: the substance in which particles are distributed
  2. Tyndall effect
    Colloidal particles scatter a beam of light passing through them. This makes the path of light visible. For example, sunlight becomes visible when passing through fog. The effect is not shown by a true solution because its particles are too small to scatter light. Tyndall effect explanation
  3. Brownian movement
    Colloidal particles move continuously in a random zig-zag manner. This is called Brownian movement.
  4. Stability
    Colloidal particles do not settle down on standing because of their small size and continuous Brownian movement.
  5. Electrical charge
    Particles of a colloid usually carry the same type of electric charge. They repel one another, helping keep the colloid stable.
  6. Filtration
    Colloidal particles pass through ordinary filter paper, so they cannot be separated by simple filtration. They can be separated by special methods such as ultrafiltration or dialysis.
  7. Coagulation
    Colloidal particles may be made to settle by adding an electrolyte, heating, or prolonged dialysis. This process is called coagulation.

Explanation of any two properties

1. Tyndall effect

When a strong beam of light is passed through a colloidal solution, colloidal particles scatter the light in different directions. Hence, the path of the beam becomes visible.
Examples:
  • Beam of a car headlight in fog
  • Sunlight passing through smoke or dusty air
  • A projector beam in a dusty room

2. Brownian movement

The dispersed particles in a colloid move continuously and randomly due to unequal collisions with molecules of the dispersion medium. This random motion is known as Brownian movement.
Importance: It prevents the colloidal particles from settling at the bottom, thereby maintaining the stability of the colloid.

Examples

Crystalloids

Crystalloids are true solutions in which solute particles are very small and can pass through a semipermeable membrane.
  • Sodium chloride solution
  • Sugar solution
  • Copper sulfate solution
  • Urea solution
  • Glucose solution

Colloids

  • Milk: liquid fat droplets dispersed in water
  • Fog: liquid water droplets dispersed in air
  • Smoke: solid particles dispersed in air
  • Jelly: liquid dispersed in a solid medium
  • Butter: water droplets dispersed in fat
  • Starch solution
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