. . Balanced Chemical Equations Recall the law of conservation of mass that you studied in Class IX; mass can neither be created nor destroyed in a chemical reaction. That is, the total mass of the elements present in the products of a chemical reaction has to be equal to the total mass of the elements present in the reactants.
In other words, the number of atoms of each element remains the same, before and after a chemical reaction. Hence, we need to balance a skeletal chemical equation. Is the chemical Eq. ( .
) balanced? Let us learn about balancing a chemical equation step by step. The word-equation for Activity . may be represented as – Zinc + Sulphuric acid → Zinc sulphate + Hydrogen The above word-equation may be represented by the following chemical equation – Zn + H SO → ZnSO + H ( .
) Let us examine the number of atoms of different elements on both sides of the arrow. Element Number of atoms in Number of atoms reactants (LHS) in products (RHS) Zn H O As the number of atoms of each element is the same on both sides of the arrow, Eq. ( . ) is a balanced chemical equation.
Let us try to balance the following chemical equation – Fe + H O → Fe O + H ( . ) Step I: To balance a chemical equation, first draw boxes around each formula. Do not change anything inside the boxes while balancing the equation. Fe + H O → Fe O + H ( .
) Step II: List the number of atoms of different elements present in the unbalanced equation ( . ). Element Number of atoms Number of atoms in reactants (LHS) in products (RHS) Fe H O To equalise the number of atoms, it must be remembered that we cannot alter the formulae of the compounds or elements involved in the reactions. For example, to balance oxygen atoms we can put coefficient ‘ ’ as H O and not H O or (H O)