Study Notes
Methods of purification involve techniques to separate and purify substances based on their physical properties.
- Filtration — a method to separate an insoluble solid from a liquid. Example: Separating chalk from water using filter paper.
- Crystallisation — a technique to form solid crystals from a solution. Example: Obtaining solid copper sulfate from its solution.
- Distillation — used to separate a pure liquid from a mixture based on boiling points. Example: Distilling salt water to obtain fresh water.
- Fractional Distillation — similar to distillation but uses a fractionating column to separate liquids with close boiling points. Example: Separating petroleum products from crude oil.
- Paper Chromatography — a method to separate mixtures based on their movement through a paper in a solvent. Example: Separating chlorophyll pigments.
Exam Tips
Key Definitions to Remember
- Filtration: Separating an insoluble solid from a liquid.
- Crystallisation: Forming solid crystals from a solution.
- Distillation: Separating liquids based on boiling points.
- Fractional Distillation: Separating liquids with close boiling points using a fractionating column.
- Paper Chromatography: Separating mixtures based on movement through paper.
Common Confusions
- Confusing crystallisation with evaporation.
- Mixing up distillation and fractional distillation.
Typical Exam Questions
- What is the purpose of filtration? To separate an insoluble solid from a liquid.
- How does distillation work? By heating a mixture to separate liquids based on boiling points.
- What is the role of a fractionating column in fractional distillation? To separate liquids with close boiling points more effectively.
What Examiners Usually Test
- Understanding of different purification methods.
- Ability to choose the correct method for a given separation task.