Class
JSS1
Term
Second Term
Week
Week 5
Topic
Separation of Mixtures
Duration
40 Minutes
Instructional Materials
- Sand and water mixture
- Salt and water solution
- Filter paper
- Funnel
- Beaker
- Evaporating dish
- Heat source (spirit lamp or gas burner)
- Glass rod
- Bottle containing muddy water
- Ink and filter paper (for chromatography)
- Condensation setup (simple distillation apparatus diagram/chart)
Reference Books
- NERDC Basic Science Curriculum for JSS
- STAN Basic Science for Junior Secondary Schools
- Evans Basic Science for Junior Secondary Schools
- Comprehensive Basic Science by A.O. Ogunniyi
Specific Objectives
At the end of the lesson, students should be able to:
- Define mixture.
- Explain the meaning of separation of mixtures.
- Identify methods of separating mixtures.
- Describe filtration, evaporation, decantation, distillation and chromatography.
- State the uses of each separation method.
- Apply separation techniques to everyday life situations.
Introduction
In our environment, substances are often found mixed together. For example, sand and water, salt and water, or oil and water.
These substances can be separated using different methods because they are mixtures.
Separation of mixtures is very important in everyday life, industries, and laboratories.
Meaning of Mixture
A mixture is a combination of two or more substances that are not chemically combined together.
Examples of Mixtures:
- Sand and water
- Salt and water
- Oil and water
- Air (mixture of gases)
- Soil
Mixtures can be separated because their components retain their original properties.
Meaning of Separation of Mixtures
Separation of mixtures is the process of dividing a mixture into its individual components using physical methods.
No new substance is formed during separation.
Methods of Separating Mixtures
The main methods include:
- Filtration
- Evaporation
- Decantation
- Distillation
- Chromatography
1. Filtration
Filtration is a method used to separate insoluble solid particles from a liquid using a filter.
Process of Filtration
- A mixture of sand and water is poured into a funnel lined with filter paper.
- The liquid passes through as filtrate.
- The solid remains on the filter paper as residue.
Uses of Filtration
- Removing sand from water
- Cleaning drinking water
- Separating tea leaves from tea
Examples
2. Evaporation
Evaporation is the process of separating a dissolved solid from a liquid by heating the mixture until the liquid turns into vapour.
Process of Evaporation
- A salt solution is heated.
- Water evaporates into the air.
- Salt remains in the container.
Uses of Evaporation
- Obtaining salt from seawater
- Drying clothes
- Producing sugar crystals
Example
3. Decantation
Decantation is the process of separating a liquid from a solid by gently pouring out the liquid without disturbing the solid.
Process of Decantation
- Muddy water is allowed to settle.
- The solid particles sink to the bottom.
- The clear water is carefully poured out.
Uses of Decantation
- Separating water from sand
- Removing oil from water
- Clearing muddy water
Example
- Sand and water after settling
4. Distillation
Distillation is the process of separating a mixture of liquids or a liquid and dissolved solid by boiling and condensation.
Process of Distillation
- The mixture is heated.
- The liquid with lower boiling point evaporates first.
- Vapour is cooled in a condenser.
- The liquid is collected as distillate.
Uses of Distillation
- Producing pure water from salt water
- Refining petroleum
- Producing distilled water for laboratories
Example
- Salt water → pure water + salt
5. Chromatography
Chromatography is a method used to separate different dissolved substances in a liquid based on their movement through a medium.
Process of Chromatography
- A drop of ink is placed on filter paper.
- The paper is dipped in water.
- Different colours move at different speeds.
- The colours separate.
Uses of Chromatography
- Separating ink pigments
- Testing food colourings
- Forensic investigations
- Drug testing
Example
- Black ink separating into different colours
Comparison of Separation Methods
| Method |
Substance Separated |
Example |
| Filtration |
Insoluble solid + liquid |
Sand and water |
| Evaporation |
Soluble solid from liquid |
Salt and water |
| Decantation |
Liquid from solid |
Muddy water |
| Distillation |
Pure liquid from mixture |
Pure water from salt water |
| Chromatography |
Dissolved substances |
Ink pigments |
Importance of Separation of Mixtures
- To obtain pure substances
- To make drinking water safe
- To produce salt and sugar
- To refine petroleum products
- To carry out laboratory experiments
- To improve industrial production
Practical Activities
Activity 1: Filtration
Mix sand and water and filter it using filter paper.
Observation:
Sand remains on filter paper while water passes through.
Conclusion:
Filtration separates insoluble solids from liquids.
Activity 2: Evaporation
Heat salt solution in an evaporating dish.
Observation:
Water disappears leaving salt behind.
Conclusion:
Evaporation separates dissolved solids from liquids.
Activity 3: Decantation
Allow muddy water to settle and pour out clear water.
Observation:
Clear water separates from sand.
Conclusion:
Decantation separates liquid from solid.
Activity 4: Chromatography
Place ink on filter paper and dip in water.
Observation:
Ink separates into different colours.
Conclusion:
Chromatography separates mixtures of coloured substances.
Conclusion
Separation of mixtures is an important process used to divide mixtures into their individual components. Different methods such as filtration, evaporation, decantation, distillation and chromatography are used depending on the type of mixture. These methods are useful in homes, industries and laboratories.
Evaluation
Answer the following questions:
- Define a mixture.
- What is separation of mixtures?
- Explain filtration.
- Describe evaporation.
- What is decantation?
- Explain distillation.
- Define chromatography.
- State three uses of filtration.
- Mention two uses of evaporation.
- Give examples of mixtures separated by decantation.
Objective Questions
Choose the correct answer from A–D.
- A mixture is ______.
A. chemically combined substance
B. pure substance
C. combination of substances not chemically combined
D. element only
Answer: C
- Filtration is used to separate ______.
A. two liquids
B. insoluble solid from liquid
C. gases
D. metals only
Answer: B
- Evaporation is used to separate ______.
A. salt from water
B. oil from water
C. sand from water
D. iron from rust
Answer: A
- The solid left on filter paper is called ______.
A. filtrate
B. residue
C. distillate
D. solution
Answer: B
- Decantation involves ______.
A. heating a mixture
B. pouring off liquid carefully
C. freezing liquid
D. burning substance
Answer: B
- Distillation involves ______.
A. freezing and melting
B. boiling and condensation
C. filtration only
D. crushing
Answer: B
- Chromatography is used to separate ______.
A. gases
B. coloured substances
C. metals
D. solids only
Answer: B
- Salt can be obtained from seawater by ______.
A. filtration
B. evaporation
C. decantation
D. sieving
Answer: B
- The liquid that passes through filter paper is called ______.
A. residue
B. filtrate
C. solid
D. vapour
Answer: B
- Which method is best for separating ink colours?
A. Decantation
B. Filtration
C. Chromatography
D. Evaporation
Answer: C
Essay Questions
- Define mixture and explain five methods of separating mixtures.
- Describe filtration with a labelled diagram.
- Explain evaporation and state its uses.
- Differentiate between filtration and decantation.
- Explain chromatography and its importance in daily life.
Assignment
- List five mixtures found at home and state how each can be separated.
- Draw and label a filtration setup.
- Explain why separation of mixtures is important in industries.
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