¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types SUBJECT:-SCIENCE Chapter No. 06 Chemical Reaction & their Types

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types INDEX 6.1 The Steps of Writing a chemical equation 6.2 Types of chemical reaction 6.3 Combination reaction 6.4 Decomposition reaction 6.5 Displacement reaction 6.6 Oxidation 6.7 The Speed of chemical reaction 6.8 Catalyst 6.9 Exothermic reaction 6.10 Endothermic reaction

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types The steps of writing a chemical equation :- 1)The molecular formulae of the reactants are written on the left hand side of the equation. 2)The molecular formulae of the products are written on the right hand side of the equation. 3)Reactant & products are connected with an arrow pointing towards the product side Reactant → Products

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types Types of chemical reactions :- 1) Combination reactions 2)Decomposition reactions 3)Dispalcement reactions

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types Combination reaction :- The chemical reaction in which single compound (product) is formed from two or more reactant is called a combination reaction. Example :- CaO ┼ H 2 O → Ca(OH) 2 ┼ energy Calcium Oxide WaterCalcium Hydroxide

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types Decomposition reaction :- The chemical reaction in which a substance is broken down into two or more substances is called decomposition reaction. Example :- 2 H 2 O → 2H 2 ┼ O 2 ↑ Electric Current Water → Hydrogen Oxygen

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types Displacement reaction :- The chemical reaction in which one constituent displaces another constituent & separates is called a displacement reaction. Example :- Zn ┼ 2HCl → ZnCl 2 ┼ H 2 ↑ ZincHydrochloric acid Zinc chloride

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types Oxidation :- A chemical reaction in which oxygen combines with an element or a compound or a reaction in which hydrogen is lost form is called oxidation. Example :- C ┼ O 2 → CO 2 ↑ Carbon Oxygen Carbon dioxide

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types The speed of chemical reaction :- depend on the following factors :- 1)The size of the reactant particles. 2)The concentration of the reactant. 3)The temperature. 4)Catalyst used in chemical reaction.

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types Catalyst :- A substance which does not take part in a chemical reaction but by its mere presence speed up a chemical reaction, is called as a catalyst. In the preparation of oxygen from potassium chlorate, manganese dioxide is used a catalyst. Manganese dioxide Raney nickel

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types Exothermic Reaction :- A reaction in which heat is given out is called exothermic reaction. The reaction between calcium oxide and water is an example of exothermic reaction. Calcium OxideWater

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std-8 th Sub-Science Chap- Chemical Reaction & Their Types Endothermic Reaction :- A reaction in which heat is absorbed is called endothermic reaction. The reaction between salt & water is an example of endothermic reaction. SaltWater

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Sub-Science Std-8 th Chap- Chemical reaction & Their types PROJECTED BY DINESH B. DABHADE B.Sc.B.Ed MAHARAJA SAYAJIRAO VIDYALAYA,SATARA