Separation of Mixtures

Introduction to Mixtures

• Mixture Definition: Two or more substances physically combined, not chemically.
• Physical Change: Involves a change in physical properties without changing chemical composition.
  • Examples: Changing states (solid, liquid, gas), dissolving, separating mixtures.

Physical Properties Utilized in Separation

• Key Properties:
  • Particle size
  • Density
  • Melting and boiling points
  • Solubility
  • Magnetism
  • Electrostatic attraction
• Pure substances retain distinct physical properties.

Techniques Based on Particle Size

• Sieving:
  • Separates particles based on size.
  • Smaller particles pass through a sieve, larger particles are collected.
  • Example: Separating gold coins from sand.

Techniques Based on Density

• Density Definition: Mass per unit volume, measured in kg/m³ or g/cm³.
• Key Separation Techniques:
  • Sedimentation
  • Decantation
  • Centrifugation
  • Separation funnels

Sedimentation and Decantation

• Sedimentation:
  • Insoluble particles settle from liquids or gases.
  • Used to separate solids from liquids (e.g., sand from water).
• Decantation:
  • Pouring off liquid from above settled insoluble particles.
  • Example: Separating clean water from sand.

Centrifugation

• Rapid spinning to separate substances by density.
• Solids move to the bottom, liquids float on top.
• Can separate immiscible liquids (e.g., milk separation).

Separation Funnels

• Separates immiscible liquids of different densities.
• More dense liquid drains first, less dense remains.
• Example: Separating water from lamp oil.

Miscibility

• Miscible Liquids: Mix in any proportion (e.g., ethanol and water).
• Immiscible Liquids: Do not mix, form distinct layers (e.g., oil and water).

Conclusion

• Summary of Techniques:
  • Sieving based on size.
  • Density-based techniques: Sedimentation, decantation, centrifugation, separation funnels.
• Emphasis on understanding physical properties and appropriate application of separation methods.

• Further Learning: Check out additional resources and videos for more lessons on chemistry separation techniques.