Solubility - Science (Grade 9)

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1. Science Shree Shitaladevi Community Secondary School www.yepnepal.com @santoshpaudel Grade - 9 [email protected]

2. UNIT: Solubility A mixture is defined as a mass obtained by mixing up two or more chemically non-reactive substances in any proportion by weight. There are two types of mixture. They are as follows : 8/31/2020 www.yepnepal.com 1

3. Types of Mixture 1. Homogeneous mixture : A homogeneous mixture is defined as a mass in which the particles of the components of the mixture are equally distributed. Examples: Sugar solution, air, alcohol water, brass, soda water etc. 2. Heterogeneous mixture A heterogeneous mixture is defined as a mass in which the particles of components of the mixture are not equally distributed. Examples: Smoke, Oily water, Sandy water, etc. 8/31/2020 www.yepnepal.com 2

4. Solubility Solution = solute + solvent Solute:  It is the component of a solution, which gets dissolved into other substance to form a solution. Solvent:  It is the substance, which dissolves solute to form a solution. Water:  It is a universal solvent that has the capacity of dissolving many substances like common salts, copper sulphate, sugar, etc. Alcohol:  It found in the form of spirit and can dissolve resin and iodine. Petrol and kerosene:  It dissolves ghee, grease, oil, fat, etc. and is used for removing clothes stain. Ether:  It is an organic solvent that can dissolve fat, oil, resin, etc. 8/31/2020 www.yepnepal.com 3

5. Saturated solution The solution in which the solvent cannot dissolve the solute anymore, at the given temperature then it is known as saturated solution at that temperature. When we dissolve solute in a solvent and there comes a time when the solute won't get dissolved anymore, then this solution is considered as saturated solution. Example: When we pour sugar in the water and stir it, the sugar keeps dissolving but on further dissolving the sugar, a state will come when the sugar will not get dissolved in the water. At this point, the solution is a saturated solution. 8/31/2020 www.yepnepal.com 4

6. Unsaturated solution T he solution which can dissolve the solute at the given temperature is known as unsaturated solution at that temperature. Solutions having low concentration of solute particles are called  dilute solution. Solutions having high concentration of solute particles are called  concentrated solution. Supersaturated Solution: The saturated solution at a higher temperature that holds excess solute than the required amount for a saturated solution at that temperature is called supersaturated solution. 8/31/2020 www.yepnepal.com 5

7. Solubility 8/31/2020 www.yepnepal.com 6 Solubility of the substance The amount of solute required to form a solution in 100 gm of solvent at a particular temperature to give saturated solution is the solubility of that solute at that temperature. The solubility of a substance at certain temperature can be given by Weight of solute (gm) Solubility = x 100 Weight of solvent (gm)

8. Solubility Effect of the temperature on solubility The relationship between increase in temperature and solubility is that the solubility is directly proportional to the increase in the temperature. i.e. At high temperature the solubility of a solution is high so it is able to dissolve more solute, but when it is cooled, the solubility of the solution decreases and due to which the solute separate out as solid. Solubility curve Solubility curve is curve obtained by the plotting the solubility of the substance at different temperature against these temperatures. 8/31/2020 www.yepnepal.com 7

9. Solubility Curve 8/31/2020 www.yepnepal.com 8

10. Solubility Curve From the solubility curve various information can be obtained which are listed below: I. Comparative study of the solubility of different solutes can be done. II .The solubility of solute at any temperature can be found out. III. The change in solubility on changes in temperature can be observed. Crystal  A solid which has certain geometrical shape and certain boiling and freezing point is called crystal. It is formed by the process of crystallization.  8/31/2020 www.yepnepal.com 9

11. Crystal Characteristics of Crystals: They are the solid particles with a definite shape. They are pure substances. They have fixed melting point. They are arranged in three dimensional patterns. Crystallization: The process in which crystals are formed by cooling a hot saturated solution of the solid substance which can give crystals is called crystallization. In other words, the process of formation of crystals is called crystallization. 8/31/2020 www.yepnepal.com 10

12. Crystalline Solid: A solid which has certain shape and certain boiling and freezing point is called crystals. The substances that can form crystals are called crystalline substances. For Example: NaCl, CuSO 4 etc. Amorphous Solid: A solid which has no fixed geometrical shape is known as amorphous. These substances can not form crystals. For Example: Glass, rubber, plastic etc. 8/31/2020 www.yepnepal.com 11

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14. Exercise 8/31/2020 www.yepnepal.com 8

15. Exercise 8/31/2020 www.yepnepal.com 9

16. Exercise 8/31/2020 www.yepnepal.com 10

17. Numerical Problems 8/31/2020 www.yepnepal.com 11

18. Numerical Problems 8/31/2020 www.yepnepal.com 12