Is matter around us pure

Is matter around us pure

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  Class-IX Subject: Science (Chemistry) Topic:Is Matter Around Us Pure Part-II
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  Content ⮚Evaporation ⮚Centrifugation ⮚Separation immiscible liquids ⮚Sublimation ⮚Chromatography ⮚Distillation ⮚FractionalDistillation ⮚Separation of Air ⮚Crystallisation ⮚Physical and Chemical Changes ⮚Pure Substances ⮚Mixture and compounds
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  Why to separate? •Separation makes it possible to study and use the individual components of a mixture. • Heterogeneous mixtures can be separated into their respective constituents by simple physical methods like Handpicking, Sieving, Winnowing, Filtration.
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  • For selectingthe correct method of separation, we have to think about the properties of the components of mixture…..
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  Different Methods ofSeparation METHODS OF SEPARATION Evaporation Centrifugation By using Separating funnel Sublimation Distillation Fractional Distillation Crystallisation Chromatography
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  Evaporation
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  Centrifugation It is themethod in which the denser particles in the mixture are forced to the bottom and the lighter particles stay at the top when the mixture is spun rapidly.
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  Separating funnel The separationof a mixture of two immiscible liquids is done by using a separating funnel. The principle is that immiscible liquids separate out in layers depending on their densities. • To separate a mixture of oil and water. • In the extraction of iron from its. Applications:
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  Sublimation Substances that changesdirectly from solid to gaseous state on heating without undergoing liquid state are called sublime substances. To separate such mixtures that contain a sublimable volatile component from a non-sublimable impurity the sublimation process is used.
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  Chromatography ⮚Chromatography is thetechnique used for separation of those solutes that dissolve in the same solvent. ⮚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. ⮚This process of separation of components of a mixture is known as chromatography. ⮚ Applications To separate ▪ Colors in a dye ▪ Pigments from natural colors ▪ Drugs from blood.
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  Chromatography
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  Simple Distillation • Itis used for the separation of the components of a mixture containing two miscible liquids that boil without decomposition and have sufficient difference in their boiling points i.e. more than 25K.
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  Fractional Distillation To separatea mixture of two or more miscible liquids for which the difference in boiling points is less than 25 K, fractional distillation process is used. 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, as shown in Fig
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  Separation of componentsof Air ⮚Air is a homogeneous mixture and can be separated into its components by fractional distillation. ⮚The air is compressed by increasing the pressure and is then cooled by decreasing the temperature to get liquid air. This liquid air is allowed to warm-up slowly in a fractional distillation column, where gases get separated at different heights depending upon their boiling points.
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  Crystallisation ⮚ Crystallization isa process that separates a pure solid in the form of its crystals from a solution. ⮚ Crystallization technique is better than simple evaporation-- 1. Some solids decompose or some, like sugar, may get charred on heating to dryness. 2. 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.
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  Purification of water Incities, drinking water is supplied from water works. A flow diagram of a typical water works is shown in Figure.
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  Physical and ChemicalChanges The interconversion of states is a physical change because these changes occur without a change in composition and no change in the chemical nature of the substance. Physical change brings change in the physical properties of matter. The burning of a candle is a Chemical change. During this change one substance reacts with another to undergo a change in chemical composition. Chemical change brings change in the chemical properties of matter and we get new substances.
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  What are PureSubstances ?
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  • Distinguish betweenhomogeneous and heterogeneous mixtures. Classify the following mixtures as homogeneous and heterogeneous: (i) Tincture of iodine (ii) Smoke (iii) Brass(iv) Sugar solution • A teacher told three students A, B and C to prepare 25% solution (mass by volume) of KOH. Student A dissolved 25 g of KOH in 100 g of water, student B dissolved 25 g of KOH in 100 mL of water and student C dissolved 25 g KOH in water and made the volume 100 mL. Which one of them has made required 25% solution? Give your answer with reason. Assignments
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  Task for theday • Take an earthen pot, some pebbles and sand. Design a small scale filtration plant that you can use to clean muddy water. ⮚ Classify the substances given in below into elements and compounds.
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  Conceptualized by Mr. YashwantV. Khandare