Study Notes
Separation and purification techniques are used to isolate and purify substances based on their physical properties such as boiling and melting points.
- Pure Substance — a single element or compound not mixed with any other substance Example: Pure milk
- Filtration — separates an insoluble solid from a liquid Example: Separating chalk from water
- Crystallisation — separates a soluble solid from a solution Example: Obtaining solid copper sulfate from its solution
- Distillation — separates a pure liquid from a mixture based on boiling points Example: Distillation of salt water to fresh water
- Fractional Distillation — separates a mixture of liquids with different boiling points using a fractionating column Example: Obtaining petrol from crude oil
- Paper Chromatography — separates components of a mixture based on their movement through a paper in a solvent Example: Separating chlorophyll pigments
Exam Tips
Key Definitions to Remember
- Pure Substance: A single element or compound not mixed with any other substance
- Filtration: A method to separate an insoluble solid from a liquid
- Crystallisation: A method to separate a soluble solid from a solution
- Distillation: A method to separate a pure liquid from a mixture
- Fractional Distillation: A method to separate liquids with different boiling points
- Paper Chromatography: A method to separate components of a mixture using paper and a solvent
Common Confusions
- Confusing distillation with fractional distillation
- Misunderstanding the role of a solvent in paper chromatography
Typical Exam Questions
- What is the purpose of filtration? To separate an insoluble solid from a liquid
- How does crystallisation work? By evaporating the solvent to leave behind crystals of the solute
- What is the principle behind distillation? Separation based on different boiling points
What Examiners Usually Test
- Understanding of different separation techniques
- Ability to suggest suitable methods for given mixtures
- Knowledge of purity indicators like melting and boiling points