Balancing Equations

The law of conservation of mass states that the total mass of the products equals the total mass of the reactants, because atoms cannot be created or destroyed.Chemical reactions rearrange the atoms by breaking existing bonds and forming new ones. In writing a chemical equation it is necessary to ensure the same number of atoms of each element are on both sides.Balanced symbol equations use the formulae of reactants and products. They show the amounts(number of moles) of reactants that react together and the relative number of moles of a product that has been formed.2Mg + O₂ → 2MgOThe equation above shows that 2 moles of magnesium will react with one mole of oxygen to give 2 moles of magnesium oxide.State symbols can also be added after the formulae in brackets to indicate what physical state the reactants and products are in.The state symbols are (s)-solid, (l)-liquid, (g)-gas and (aq)-aqueous.2Mg(s) + O₂(g) → 2MgO(s)