Question

Why should an equation be balanced? Explain with the help of a simple equation.

Answer 1

Hint: In order to answer the given question, we first need to understand the concept of law of conservation of masses. The Law of Conservation of Mass dates from Antoine Lavoisier's 1789 discovery that mass is neither created nor destroyed in chemical reactions. We know that a balanced chemical equation has the same number of atoms for each element that occurs in the chemical reaction. We have to calculate the number of atoms for a given element by multiplying the coefficient of any formula containing that element by the subscript of the element present in the formula.

Complete step by step answer:
We have to remember that the law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations.
According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.
The law of conservation of mass is useful for a number of calculations and can be used to solve for unknown masses, such as the amount of gas consumed or produced during a reaction.
Thus, it can be rightly said that an equation (chemical equation to be more specific) must be balanced so that it obeys the law of conservation of masses. The number of atoms of reactants should be equal to the number of atoms of the products formed after the successful completion of a reaction.
If we observe an element that is seen in more than time in one formula on a given side of the equation, we have to compute the number of atoms and then add them together.
An unbalanced equation is said to have an unequal number of atoms on either side of the reaction. For example,
\[KMn{O_4} \to {K_2}Mn{O_4} + Mn{O_2} + {O_2}\] (Unbalanced)
In this reaction of decomposition of potassium permanganate, the equation is unbalanced. The number of atoms of K, Mn and O is unequal before and after the reaction, thus disobeying the law of conservation of mass. However, on balancing the reaction, we have
\[2KMn{O_4} \to {K_2}Mn{O_4} + Mn{O_2} + {O_4}\](Balanced)
The above equation obeys the law of conservation of masses since the number of atoms of all the elements taking part in the reaction are equal before and after the reaction.

Note: It must be noted that law of conservation of masses applies not only to simple reactions but also to ionic reactions. In case of ionic reactions, law of conservation of masses hold true along with law of conservation of charges as well. It states that the net charge of either side of the reactions must be equal before and after the reaction. In other words, all chemical reactions (ionic or non-ionic) must obey both the laws of conservation of mass and charge.