The verification of each of the following chemical laws was well established with examples to simplify it. THE LAW OF CONSERVATION OF MASS This Law was established by Lavoisier, a French Chemist. This law states that matter is neither created nor destroyed during chemical reaction but changes from one form to another. This means that in a chemical reaction, the total mass of all reacting substances (i.e. the reactants) is equal to the total mass of the products. THE LAW OF DEFINITE PROPORTIONS OR CONSTANT COMPOSITION This Law was proposed by Proust (1755-1826). The Law of Definite Proportions states that all pure samples of a particular chemical compound contain similar elements combined in the same proportion by mass. THE LAW OF MULTIPLE PROPORTIONS The law of Multiple Proportions states that if two elements, A and B, combine to form more than one chemical compound, the various masses of one element, A which combine separately with a fixed mass of the other element, B, are in simple multiple ratios. BALANCING CHEMICAL EQUATION WITH CALCULATION A chemical equation is a shorthand expression for a chemical change or reaction. It shows among other things the arrangement of atoms that are involved in the reaction. When balancing an equation, you must remember the following: Know the reacting substances and the products formed. Know the chemical formulae for all the substances. Write, in front of the formulae, coefficients that will balance the equation. Common gases, such as oxygen, hydrogen, chlorine and nitrogen, in the free state, are diatomic, e.g. O2, H2, Cl2 and N2 Other elements in the free state, such as sodium, potassium, copper and iron, are represented by their atomic symbols, e.g. Na, K, Cu and Fe.