Separation Of mixtures


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1 Made by: Ruchika Maheshwari Class : IX – B Roll No. : 9227 Separation Of Mixtures

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2 Mixtures are constituted by more than one kind of pure form of matter, known as a substance. We can also say that a mixture contains more than one substance. MIXTURES Mixture of dry fruits Soil Air is a mixture of various gases.

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3 We have learnt that most of the natural substances are not chemically pure. Different methods of separation are used to get individual components from a mixture. Separation makes it possible to study and use the individual components of a mixture. SEPARATION OF MIXTURES

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4 Fill half a beaker with water. Put a watch glass on the mouth of the beaker. Put few drops of ink on the watch glass. Now start heating the beaker. We do not want to heat the ink directly. You will see that evaporation is taking place from the watch glass. Continue heating as the evaporation goes on and stop heating when you do not see any further change on the watch glass. Observe carefully and record your observations. How Can We Obtain Colored Component (Dye) From Blue/Black Ink? We find that ink is a mixture of a dye in water. Thus, we can separate the volatile component (solvent) from its non-volatile solute by the method of evaporation.

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5 • Take some full-cream milk in a test tube. • Centrifuge it by using a centrifuging machine for two minutes. If a centrifuging machine is not available in the school, you can do this activity at home by using a milk churner, used in the kitchen. How Can We Separate Cream From Milk?

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6 Sometimes the solid particles in a liquid are very small and pass through a filter paper. For such particles the filtration technique cannot be used for separation. Such mixtures are separated by centrifugation. The principle is that the denser particles are forced to the bottom and the lighter particles stay at the top when spun rapidly. Applications:- • Used in diagnostic laboratories for blood and urine tests. • Used in dairies and home to separate butter from cream. • Used in washing machines to squeeze out water from wet clothes. CENTRIFUGATION Centrifuging Machine

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7 1. Let us try to separate kerosene oil from water using a separating funnel. 2. Pour the mixture of kerosene oil and water in a separating funnel. 3. Let it stand undisturbed for sometime so that separate layers of oil and water are formed. 4. Open the stopcock of the separating funnel and pour out the lower layer of water carefully. 5. Close the stopcock of the separating funnel as the oil reaches the stop-cock. Applications • To separate mixture of oil and water. • In the extraction of iron from its ore, the lighter slag is removed from the top by this method to leave the molten iron at the bottom in the furnace. How Can We Separate A Mixture Of Two Immiscible Liquids? Separating Funnel Kerosene oil Water Stopcock Separation of immiscible liquids The principle is that immiscible liquids separate out in layers depending on their densities.

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8 We have learnt before that ammonium chloride changes directly from solid to gaseous state on heating. So, to separate such mixtures that contain a sublimiable volatile component from a non-sublimiable impurity (salt in this case), the sublimation process is used. Some examples of solids which sublime are ammonium chloride, camphor, naphthalene and anthracite. How Can We Separate A Mixture Of Salt And Ammonium Chloride? Separation of ammonium chloride and salt by sublimation.

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9 The ink that we use has water as the solvent and the dye is soluble in it. As the water rises on the filter paper it takes along with it the dye particles. Usually, a dye is a mixture of two or more colors. The colored component that is more soluble in water, rises faster and in this way the colors get separated. This process of separation of components of a mixture is known as chromatography. Kroma in Greek means color. This technique was first used for separation of colors, so this name was given. Chromatography is the technique used for separation of those solutes that dissolve in the same solvent. With the advancement in technology, newer techniques of chromatography have been developed. Applications To separate:- • colors in a dye. • pigments from natural colors. • drugs from blood. CHROMATOGRAPHY

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10 • Let us try to separate acetone and water from their mixture. • Take the mixture in a distillation flask. Fit it with a thermometer. • Arrange the apparatus as shown in the diagram. • Heat the mixture slowly keeping a close watch at the thermometer. • The acetone vaporizes, condenses in the condenser and can be collected from the condenser outlet. • Water is left behind in the distillation flask. How Can We Separate A Mixture Of Two Miscible Liquids? Separation of two miscible liquids by distillation

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11 The method which is used for the separation of components of a mixture containing two miscible liquids that boil without decomposition and have sufficient difference in their boiling points is called Distillation. To separate a mixture of two or more miscible liquids for which the difference in boiling points is less than 25 K, fractional distillation process is used, for example, for the separation of different gases from air, different factions from petroleum products etc. The apparatus is similar to that for simple distillation, except that a fractionating column is fitted in between the distillation flask and the condenser. A simple fractionating column is a tube packed with glass beads. The beads provide surface for the vapours to cool and condense repeatedly. DISTILLATION Distillation

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12 How Can We Obtain Different Gases Of Air? Air is a homogeneous mixture and can be separated into its components by fractional distillation. Air Liquid Air Compressing and Cool by increasing pressure and decreasing temperature. Allow to warm up slowly in fractional distillation column. Gases get separated at different heights. Flow diagram shows the process of obtaining gases from air

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13 Take some (approximately 5g) impure sample of copper sulphate in a china dish. Dissolve it in minimum amount of water. Filter the impurities out. Evaporate water from the copper sulphate solution so as to get a saturated solution. Cover the solution with a filter paper and leave it undisturbed at room temperature to cool slowly for a day. You will obtain the crystals of copper sulphate in the china dish. This process is called crystallization. How Can We Obtain Pure Copper Sulphate From An Impure Sample? Pure copper Sulphate

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14 The crystallization method is used to purify solids. For example, the salt we get from sea water can have many impurities in it. To remove these impurities, the process of crystallization is used. Crystallization is a process that separates a pure solid in the form of its crystals from a solution. Crystallization technique is better than simple evaporation technique as –some solids decompose or some, like sugar, may get charred on heating to dryness. Some impurities may remain dissolved in the solution even after filtration. On evaporation these contaminate the solid. Applications • Purification of salt that we get from sea water. • Separation of crystals of alum (phitkari) from impure samples. CRYSTALLIZATION

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15 Water purification system in water works By choosing one of the above methods according to the nature of the components of a mixture, we get a pure substance. With advancements in technology many more methods of separation techniques have been devised. In cities, drinking water is supplied from water works.

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