TYPES OF CHEMICAL REACTIONS · Part 2

in a chemical equation, the number of atoms of the reactants and that of the products must be equal. The number of hydrogen and oxygen atoms in the reactants and the products are not MORE TO KNOW The phases or the physical state of the substances in a chemical reaction are denoted in short form within a bracket, as the subscript of the formula, of the respective substances. For example, when solid potassium reacts with liquid water, it produces hydrogen gas and potassium hydroxide solution. All these information of the reaction is given in the chemical equation as shown below: 2K (s) + 2H O (I) → 2KOH (aq) + H (g) Symbol Phase or physical state s Solid l Liquid g Gas aq Aqueous Solution Types of Chemical Reactions . TYPES OF CHEMICAL REACTIONS Classification based on the nature of rearrangements of atoms So far you studied about a chemical reaction and how it can be described as a chemical equation. A large number of chemical reactions are taking place around us every day.Are they taking place in a similar way? No. Each reaction involves different kinds of atoms and hence the way they react also differs. Thus, based on the manner by which the atoms of the reactants are rearranged, chemical reactions are classified as follows. (a) Combination reactions A combination reaction is a reaction in which two or more reactants combine to form a compound. It is otherwise called 'synthesis reaction' or 'composition reaction'. When a reactant ‘A’ combines with ‘B’, it forms the product ‘AB’. The generalised scheme of a combination reaction is given below: