Lecture Notes: Separating Mixtures

Types of Mixtures

• Solution: A homogeneous mixture where one substance (solute) is completely dissolved in another (solvent).
  • Example: Coffee drip
• Colloid: A mixture where very small particles of one substance are evenly distributed throughout another without settling out.
  • Example: Mayonnaise, Gelatin
• Suspension: A heterogeneous mixture containing solid particles that are sufficiently large for sedimentation.
  • Example: Vinegar and cooking oil, Flour and water

Methods of Separating Mixtures

1. Decantation

• Definition: Technique to separate mixtures of solid and liquid, or two liquids of different densities.
• Process: Allow the mixture to stand until the heavier solid or liquid separates naturally; pour off the lighter liquid.
• Examples:
  • Sand and water: Wait for sand to settle, then pour out water.
  • Oil and water: Separate oil by scooping.

2. Evaporation

• Definition: Method where liquid turns into gas, leaving solid solute behind.
• Example:
  • Producing salt from seawater by evaporating water under the sun.
  • Heating a salt solution allows water to evaporate, leaving salt.

3. Filtration

• Definition: Separates insoluble solid from liquid using a filter.
• Process:
  • Use filter paper/cloth to catch solid particles (residue) while allowing liquid (filtrate) to pass through.
• Example: Filtering a mixture of liquid and solid particles.

4. Magnetism

• Definition: Separates metals from non-metals using magnets.
• Example: Mixture of sand and iron filings.
  • Iron filings are attracted to a magnet, separating them from sand.

5. Sieving (Sifting)

• Definition: Separates mixtures with large and small particles using a strainer/screen.
• Examples:
  • Sand from gravel
  • Large particles of flour

6. Winnowing

• Definition: Separates heavier components from lighter substances using wind.
• Equipment: Winnower

7. Flotation

• Definition: Separates substances based on density differences.
• Example:
  • Leaves floating in water.
  • Rice bran floating in water.

8. Distillation

• Definition: Separates liquids based on different boiling points.
• Process: Heats mixture; lowest boiling point substance becomes vapor, condenses back to liquid.
• Application: Homogeneous solutions

9. Physical Separation (Hand Picking)

• Definition: Separates solid components of a mixture using hands or forceps.
• Example: Sorting nuts from mixed nuts.

10. Chromatography

• Definition: Separates components based on movement across another surface.
• Application: Separating colored substances like inks and plant dyes.

Quiz

• Sieving: Separating big and fine particles using a strainer.
• Magnetism: Separating metals and non-metals using magnets.
• Evaporation: Separating soluble solid from liquid using heat.
• Hand Picking: Separating solid components of a heterogeneous mixture by hand.
• Winnowing: Separating heavier from lighter objects using wind.

Conclusion

• Review of different separation techniques.
• Interactive quiz to test understanding.

End of Lecture