| a. Endothermic reaction |
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| → The reaction in which heat is absorbed is called an endothermic reaction. The heat is either absorbed from the surroundings or it has to be supplied from outside. e.g. When potassium nitrate dissolves in water, heat is absorbed during the reaction and the temperature of the solution falls. KNO3(s) + H2O(l) + Heat → KNO3(aq) 2 Marks |
| b. Combination reaction |
| → When two or more reactants combine in a reaction to form a single product, it is called a combination reaction. e.g. Ammonia gas reacts with hydrogen chloride gas to form ammonium chloride. NH3(g) + HCl(g) → NH4Cl(s) 2 Marks |
| c. Balanced Equation |
| → In a chemical reaction, the number of atoms of the elements in reactants is the same as the number of atoms of those elements in the products. An equation depicting this is known as a Balanced Equation. e.g. Silver Nitrate reacts with Sodium Chloride to form Sodium Nitrate and a precipitate of Silver Chloride. AgNO3 + NaCl → NaNO3 + AgCl In the above equation, the number of atoms of the elements in the reactants is same as their number in products. Thus, this is a balanced equation. 2 Marks |
| d. Displacement Reaction |
| → The reaction in which the place of the ion of a less reactive element in a compound; is taken by another more reactive element by formation of its own ions, is called a Displacement Reaction. e.g. Iron reacts with copper sulphate to form ferrous sulphate and copper. Fe(s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s) + Heat In this reaction, more reactive iron atoms replace the less reactive copper atoms from the copper sulphate solution. 2 Marks |
Watch Video: (3:39) |
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A video showing reaction of Iron nails with Copper Sulphate: |
This page was last modified on
08 August 2019 at 23:43