Chapter 9 Methods of Separation in Everyday Life Revision Notes Class 6 Science
Methods of Separation in Everyday Life Chapter Notes Class 6
- Introduction
- Handpicking
- Threshing
- Winnowing
- Sieving
- Evaporation
- Sedimentation and Decantation
- Filtration
- Churning
- Magnetic Separation
- Key Points
Introduction
Separation of things is important because it helps us organize and manage different materials effectively. For example, separating recyclables from trash allows us to recycle and reuse materials, reducing waste and conserving resources. In science and industry, separation techniques help us obtain pure substances, making it easier to study them or use them in various applications. Overall, separation improves efficiency, safety, and sustainability in many areas of life.
For Example Ria and her brother Aryan visit their grandparents' farm. They notice their grandparents sorting vegetables. Curious, they ask why. Their Dadi explains, "We clean and sort them to make sure they’re fresh for cooking." Excited, Ria and Aryan help wash the vegetables, learning how to remove dirt before cooking.
Different Methods of Separation
1. Handpicking
- Handpicking is a method used to separate small quantities of different substances from a mixture based on differences in size, colour, and shape.
- A mixture is a combination of two or more substances that are physically mixed together
- For example, when separating small stones and husk from wheat or rice. If the particles to be removed are present in small amounts and can be easily picked by hand, this method is convenient and effective.
Do you know what is handpicking?
Yes, a good example of handpicking is when Seema separates whole black peppers from the vegetable pulao using his hands. This shows how handpicking is used to remove unwanted substances from a mixture.
2. Threshing
- Threshing is the process of separating grains from the harvested stalks by beating them.
- Example: Separating wheat grains from wheat stalks by beating them with sticks or using a mechanical thresher.
3. Winnowing
Winnowing uses wind or blowing air to separate heavier grains from lighter chaff. The wind blows away the lighter chaff, while the heavier grains fall to the ground.
- Winnowing is a method of separating lighter particles from heavier particles using wind or blowing air.
- Example: Separating husk from grains of wheat or rice by using a winnowing basket.
Threshing Machines: How They Work
- Threshing machines, known as threshers, are technological advancements designed to separate grains from stalks and husk.
- These machines perform two tasks at once: threshing, which is separating the grains from the stalks, and winnowing, which is removing the lighter husk from the grains.
- By using threshers, the process of separating grains becomes faster and more efficient.
4. Sieving
- Sieving lets the tiny flour particles pass through the small holes in the sieve.
- Example: Separating bran from wheat flour.
What happens if the holes in a sieve are larger than the particles being sieved?
If the holes are larger than the particles, both the fine and larger particles will pass through, making the sieving process ineffective.
5. Evaporation
- Evaporation involves converting a liquid into vapor to separate it from dissolved solids.
- Example: Obtaining salt from seawater by evaporating the water.
How is salt obtained from seawater?
Salt is obtained by allowing seawater to evaporate in shallow pits. As the water evaporates, it leaves behind a solid mixture of salts, including common salt, which is then purified.
Ayurveda: The Ancient Indian Healing System
- Ayurveda is a traditional Indian system of health and medicine that focuses on holistic well-being.
- In Ayurveda, herbs and plant parts such as roots, leaves, flowers, and seeds are used as natural remedies to treat various health issues.
- To prepare these plant materials for use, they are often dried in the shade . This process helps remove excess moisture while preserving the medicinal properties of the plants.
6. Sedimentation and Decantation
- Sedimentation is the process where heavier, insoluble particles settle down at the bottom of a liquid.
- Decantation involves tilting the container to pour off the liquid, leaving the settled solid behind.
7. Filtration
- Filtration is a method of separating insoluble solids from a liquid using a filter medium.
- Example: Filtering tea leaves from tea using a strainer.
What do you observe when filtering muddy water using filter paper?
When filtering muddy water through filter paper, the mud particles are trapped in the filter paper as residue, while clear water passes through and is collected as filtrate in the conical flask.
Different Materials Used as Filters
- Other than filter paper, various materials like cotton, charcoal, and sand can also be used as filters.
- The choice of filter material depends on the size of the particles that need to be removed. For example:
- Cotton is good for trapping larger particles.
- Charcoal can be used to remove impurities and odors.
- Sand is effective for filtering out smaller particles.
The Evolution of Tea Bags
- Tea bags were first made from soft materials like silk because silk could hold the tea leaves while allowing hot water to pass through.
- Silk was chosen because it was strong and didn't break apart when it came into contact with hot water.
- Later on, people began using gauze or muslin for making tea bags.
- Eventually, the use of filter paper became common, and today, most tea bags are made from this material.
8. Churning
- Churning is the process of agitating a liquid mixture to separate lighter components from heavier ones.
- Example: Separating butter from curd by churning.
9. Magnetic Separation
- Magnetic separation uses magnets to separate magnetic substances from non-magnetic ones.
- Example: Separating iron nails from sawdust using a magnet.
Separation of Scrap Iron from Waste
- In various industries, waste material frequently includes scrap iron.
- To efficiently separate this scrap iron from the waste heap, recyclers employ magnets attached to cranes.
- The magnets attract the iron articles, allowing for easy removal.
- Once separated, the scrap iron can be recycled and reused, contributing to sustainability and resource conservation.
Key Points
- Handpicking: Manual removal based on size, color, or shape.
- Threshing: Separating grains from stalks by beating.
- Winnowing: Using wind to separate lighter husk from heavier grains.
- Sieving: Using a sieve to separate particles of different sizes.
- Evaporation: Converting liquid to vapor to separate dissolved solids.
- Sedimentation and Decantation: Allowing heavy particles to settle and pouring off the liquid.
- Filtration: Using a filter medium to separate insoluble solids from liquids.
- Churning: Agitating a mixture to separate lighter components.
- Magnetic Separation: Using magnets to separate magnetic from non-magnetic substances.