Is Matter Around Us Pure ? CLASS - 9

This PowerPoint Presentation will help the students of Class 9 to rejuvenate and to revise what they have learnt so far and to clear their doubts regarding any topic in this Chapter.

1. IS MATTER AROUND US PURE ?

2. MATTER Pure Substances Mixtures Elements Compounds Homogeneous Mixture Heterogeneous Mixture

3. PURE SUBSTANCES Pure Substances are substances that are made up of only one kind of particles and has a fixed composition. For e.g., gold, water, bromine, salt, chlorine, etc. Pure substances are further classified as Elements and Compounds . Elements – An Element is a substance that consists of only one type or kind of atom. It is a pure substance as it cannot be broken down or transformed into a new substance by using physical or chemical means. They can be classified as Metals , Non-Metals and Metalloids . Compounds – A Compound is also pure substance, when two or more elements are combined chemically in a fixed ratio. These substances can be broken down into separate elements by chemical methods.

4. METALS The properties of Metals are:- They have a Luster (shine). They have a silvery – grey or a golden – yellow color. They are Good Conductors of heat and electricity. They are Ductile (can be beaten up into wires). They are Malleable (can be beaten up into sheets). They are Sonorous (produce ringing sounds when hit). They are Hard . For Examples – Gold, Silver, Iron, Copper, Aluminum, Potassium, etc .

5. NON – METALS The properties of Non – Metals are:- They do not have a Luster (shine). They display a variety of colors. They are Poor Conductors of heat and electricity. They are Non - Ductile (can’t be beaten up into wires). They are Non – Malleable (can’t beaten up into sheets). They are Non – Sonorous (do not produce ringing sounds when hit). They are not Hard . For Examples – Diamond, Coal, Oxygen, Chlorine, Sulphur, etc.

6. METALLOIDS Elements that have intermediate properties of both metals and non-metals, they are called Metalloids . Examples are boron, silicon, germanium etc. The properties of Metalloids are:- Metalloids look like Metals , but behave like Non-Metals . Metalloids are Brittle , Shiny substances. They are Semi – Good Conductors of heat and electricity. Metalloids are known to form Weakly Acidic Oxides . They have the ability to form Metallic Alloys .

7. MIXTURES When two or more substances mix with each other without participating in a chemical change, the resulting substance is called a Mixture . The properties of Mixtures are:- The Components of a Mixture each keep their Original Properties . The Separation of Components can be Easily Done . The Proportion of the Components is Variable . There are two types of Mixtures:- Homogeneous Mixtures – Alloys, Solutions Heterogeneous Mixtures – Suspension, Colloids

8. ALLOYS Alloys are mixtures of two or more metals or a metal and a non-metal and cannot be separated into their components by physical methods. It is considered as a mixture because it shows the properties of its constituents and can have variable composition. An Alloy is Homogeneous Mixture . For example – Brass, Bronze, Cast Iron, 18K Gold, etc.,

9. TRUE SOLUTIONS A Solution is a Homogeneous Mixture of two or more substances. It has a Solvent and a Solute . Examples: A Solution of Sugar in Water is a Solid in Liquid Solution. A Solution of Iodine in Alcohol known as ‘ Tincture of Iodine ’, has iodine as the solute and alcohol as the solvent. Aerated drinks like Soda Water etc., are Gas in Liquid solutions. Air is a mixture of Gas in Gas . It is a Homogeneous Mixture .

10. PROPERTIES OF SOLUTIONS The properties of Solutions are:- The particles of a solution are smaller than 1 nm ( meter) in Diameter . So, they cannot be seen by naked eyes. Because of very small particle size, they do not scatter a beam of light passing through the solution. So, the Path of Light is not visible in a solution. The solute particles cannot be separated from the mixture by the process of Filtration . The solute particles do not settle down when left undisturbed, that is, a solution is Stable . IMPORTANT – 1. Solvent – The component of the solution that dissolves the other in it (present in larger amount) is called the Solvent . 2. Solute – The component of the solution that is dissolved in the solvent (present in lesser quantity) is called the Solute .  

11. CLASSIFICATIONS OF SOLUTIONS There are three types of solutions:- Saturated Solution – A Solution that has dissolved as much solute as it is capable of dissolving, is said to be a Saturated Solution . Unsaturated Solution – If the amount of solute contained in a solution is less than the saturation level, it is called an Unsaturated Solution . Supersaturated Solution – A Supersaturated Solution is a solution that contains more than the maximum amount of solute that is capable of being dissolved at a given temperature.

12. CONCENTRATION OF A SOLUTION The Concentration of a Solution is the amount of solute present in a given amount (mass or volume) of solution, or the amount of solute dissolved in a given mass or volume of solvent. Concentration of the Solution = Solubility – The amount of the solute present in the saturated solution at this temperature is called its Solubility .  

13. TYNDALL EFFECT The Tyndall Effect is the phenomenon in which the particles in a colloid scatter the beams of light that are directed at them. It can be observed when sunlight passes through the canopy of a dense forest. In the forest, mist contains tiny droplets of water, which act as particles of colloid dispersed in air.

14. SUSPENSION The properties of a Suspension are:- Suspension is a Heterogeneous Mixture . The particles of a suspension can be Seen by the Naked Eye . The Particles can be separated from the mixture by the process of Filtration . The solute particles settle down when a suspension is left undisturbed, it is Unstable . The particles of a suspension Scatter a Beam of Light passing through it and make its path visible.

15. COLLOIDAL SOLUTION The properties of a Colloidal Solutions are:- A Colloid is a Heterogeneous Mixture . The Size of Particles of a colloid is too Small to be individually Seen by Naked Eyes . They do not settle down when left undisturbed, it is Stable . They cannot be separated from the mixture by the process of Filtration . Colloids are big enough to Scatter a Beam of Light passing through it and make its path visible.

16. COMPONENTS OF A COLLOID The components of a colloidal solution are the Dispersed Phase and the Dispersion Medium . Dispersed Phase – The solute-like component in a colloid is called Dispersed Phase . Dispersion Medium – The component in which the dispersed phase is suspended is known as the Dispersing Medium .

17. SEPARATION OF COMPONENTS The Separation of Components can be done using the following techniques:- Centrifugation Separating Funnel Sublimation Distillation Fractional Distillation Chromatography Crystallization

18. CENTRIFUGATION The Principle of Centrifugation is that the denser particles are forced to the bottom and the lighter particles stay at the top when spun rapidly. Applications -1. Used in Diagnostic Laboratories for Blood and Urine Tests . 2. Used in Dairies and Home to separate Butter from Cream . 3. Used in Washing Machines to squeeze out Water from Wet Clothes .

19. SEPARATING FUNNEL The Principle of Separating Funnel is that immiscible liquids separate out in layers depending on their densities. Applications – 1. To separate Mixture of Oil and Water . 2. 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.

20. SUBLIMATION Ammonium Chloride changes directly from solid to gaseous state on heating. So, to separate a mixtures that contain a sublimable volatile component from a non-sublimable impurity (salt), Sublimation is used. For Example:- Camphor, Naphthalene, Anthracene, Iodine and Dry Ice.

21. DISTILLATION Distillation 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.

22. FRACTIONAL 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 is used. For Example:- The Separation of Gases from Air , 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 vapors to cool and condense repeatedly.

23. SEPARATION OF GASES FROM AIR Air is a Homogeneous Mixture and can be separated by Fractional Distillation .

24. OBTAINING GASES FROM AIR

25. CHROMATOGRAPHY The process of separation of components of a mixture is known as Chromatography . ‘ Kroma ’ in Greek means ‘ Color ’. Applications – 1. To separate Colours in a Dye . 2. To separate Pigments from Natural Colours . 3. To separate Drugs from Blood .

26. CRYSTALLISATION The Crystallization method is used to purify solids. It is a process that separates a pure solid in the form of its crystals from a solution. Applications – 1. Purification of Salt that we get from Sea – Water . 2. Separation of Crystals of Alum from its Impure Sample .

27. PHYSICAL CHANGES VS. CHEMICAL CHANGES PHYSICAL CHANGES Physical change is a Temporary change. In a physical change, no new substance is formed. Physical change is easily Reversible . In a physical change, the composition of the substance remains the same despite its molecules being rearranged. For Example – Tearing of Paper . CHEMICAL CHANGES Chemical Change is a Permanent change. In a chemical change a new substance is formed. Chemical changes are Irreversible . In a chemical change, molecular composition of the substance is changed entirely. For Example – Rusting of Iron .

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