A chemical equation is known to be balanced if the total number of moles of elements at the reactant is equal to that of the product.
For the reaction between sodium chloride (NaCl) and potassium nitrate (KNO₃), the balanced reaction is given as;
[tex]\text{NaCl}+\text{KNO}_3\rightarrow KCl+NaNO_3[/tex]You can see that the reactant ions exchange places to form new products (potassium chloride and sodium nitrate). This shows that the equation is a double displacement reaction