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Presentation on theme: "SEPARATION OF SUBSTANCES FROM MIXTURES"— Presentation transcript:

Science for grade 6 Chapter - 5

2 Mixtures Mixture is a combination of two or more substances.
It consists of two or more different substances that are mixed physically but not chemically combined. They do not have well defined specific properties. Substances can be easily separated from a mixture by physical methods.

3 Examples of Mixtures Rock-mixture of different kinds of rocks
Sandwich- mixture of bread, meat, tomato Soda- mixture of sugar and water Lime Juice- mixture of Lime, sugar, salt and water

4 Separation of Substance of Mixtures
Identify the different ways of separating mixtures. Determine how diffèrent ways are used to separate mixtures. Identify the ways in which Hand Picking, Threshing, Winnowing, Sieving, Magnetic Attraction, Sublimation, Evaporation, Crystallization, Sedimentation & Decantation, Loading, Filtration, Distillation, Centrifugation, and Paper Chromatography can be used in daily life. Why do we separate substances of mixture? To separate useful and non-useful substances. To get rid of impurities. To use the substances of a mixture separately.

5 Methods of separating substances from a mixture
Hand Picking Threshing Winnowing Sieving Sedimentation & Decantation Filtration Evaporation Distillation Sublimation Magnetic Separation Method Separating Funnel Method

6 1. Hand Picking The components of a solid-solid mixture can be separated by hand picking. This is only useful when the particles are large enough to be seen clearly. It is the most commonly used method of separation. For example separating pebbles from rice or dal separating grass from mint leaves separating parts of a salad

7 2. Threshing Threshing is the method that generally used by the farmers to separate the grains from the stalks after harvesting. The dried stalks are beaten or threshed to separate the grains. However, in large farms threshing is done by using threshing machines.

8 3. Winnowing Components of a mixture are separated by wind or by blowing air called winnowing method of separation. In Winnowing the mixture is allowed to fall from a height, the lighten components get separated from the heavier ones because of wind or air blow. It is the common method used by farmers. They stand on a raised platform and allow the threshed food grains to fall slowly on ground. The wind carries lighter husk and heavier grains drop on the ground. Winnowing

9 4. Sieving Seiving is used to separate minute particles of different size passing it through a sieve. Different sized sieves are used to separate different types of mixture containing minute particles. Sieve is a device containing tiny holes and separates wanted elements from unwanted material. Pebbles and stones are removed from sand by sieving Sieving

10 5. Sedimentation & Decantation
When the heavier component in a mixture settles after water is added to it, the process is called sedimentation. When the water (along with the dust) is removed, the process is called decantation. This is a quick but rough method of sepataing a mixture of liquid and un dissolved solid. Separating two components of a mixture by sedimentation and decantation

11 Example of Sedimentation & Decantation
The mixture of sand and water is taken in a beaker and allowed to stand for sometime. The sand being heavier than water and insoluble in water settles at the bottom of the beaker. This settling down of the particles in lower part of the container is called sedimentation. Take another beaker and put a glass rod in a slanting position. Slowly take the first beaker and pour the water gently on the glass rod. This transfer of the water is called decantation. Sedimentation & Decantation

12 6. Filtration Filtration is commonly the mechanical or physical operation which is used for the separation of solids from fluids (liquids or gases) by interposing a medium through which only the fluid can pass. Example:- Using a coffee filter to separate the coffee flavor from the coffee beans.

13 7. Evaporation Boiling point of a liquid is the minimum temperature at which the liquid begins to boil. You know that boiling point of water is 100oc at sea level. After reaching this temperature if you still heat it, water gradually turns into vapour. This process is called evaporation. Example of evaporation:-

14 8. Distillation Distillation the process by which a mixture is separated by heating a solution and condensing using a cooling tube. Example:-Water is taken in a distillation flask and heated, water boils and turns into vapour and it is collected in another flask called condenser. The vapours get condensed to water. This water is the purest water. It is free from any salt. This pure water is called distilled water. The salt remains in distillation flasks. Distilled water is used in the preparation of medicines. It is also used in some batteries.

15 9. Sublimation The process in which a solid changes directly into vapour state on heating is called sublimation. Example:-Take some iodine crystals in a china dish. Crush them and mix with some salt. Cover the china dish with a funnel. Keep a test tube inverted on the mouth of the funnel. Heat the china dish, iodine will be converted into vapour and gets collected on the inner wall of the funnel. Take out the test tube and allow the funnel to cool. You will observe small crystals of iodine stuck to the sides of the funnel.

16 10. Magnetic Separation Method
Take some iron filings in a china dish. Add some sugar to it. Take a magnet. Hold it with a paper cover over the mixture. Iron filings get attracted to the magnet. Only sugar remains in the china dish. This method is known as magnetic separation method. This method is used to separate magnetic substances from others. Example:- Iron filings being separated by a magnet

17 11. Separating funnel method
Liquids which do not mix with each other are called immiscible liquids. They can be sepated using an instrument called separating funnel. Example:- Take a separating funnel. Pour some water and kerosene into the separating funnel. Stir well and keep it undisturbed for a few minutes. Water being heavier than kerosene forms the upper layer. Place a beaker below the separating funnel. Open the tap and allow water to fall drop by drop into the beaker. Close the tap when all the water runs down. Only kerosene remains in the funnel. Separation of immiscible liquids.

18 Remember Mixture is a physical combination of two or more substances.
Substances in a mixture are separated by physical methods. Hand picking, threshing, winnowing, sieving, sedimentation and decantation, filtration, evaporation, sublimation, magnetic separation and separating funnel method are some of the simple methods of separating substances of a mixture. Hand picking method is used to separate slightly large sized particles present in small quantity. Grains are separated from their stalks by threshing. Lighter and heavier particles in a mixture are separated by wind by winnowing. Very small particles of different size are separated by sieving. Undissolved solid is separated from the water by sedimentation, decantation and filtration.

19 Continue.. Evaporation is the process in which a liquid is converted into its vapour. Dissolved solid from water is separated by evaporation method. Pure water is obtained by distillation method. Sublimation is the process in which a solid is directly converted into vapour. Magnetic substance in a mixture is separated by magnetic separation method. Immiscible liquids are separated by separating funnel method.





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