Question

Is this equation \[{\text{Mg}} + HCl \to MgC{l_2} + {H_2}\] balanced or not?

Answer 1

Hint: A balanced chemical equation follows the Law of conservation of mass which suggests that the number of atoms of each element participating in a reaction should also remain the same. If the mass is not conserved, then the equation is not balanced.

Complete answer:
Chemical reactions can be written on the basis of certain laws of chemical combination. One of these laws is the Law of conservation of mass. According to this law the total matter in a reaction remains conserved i.e. it is not possible to create or destroy the mass of atoms in a reaction.
For the law to be followed, the chemical equation of a reaction must be balanced. A balanced chemical equation is an equation that contains the same number of atoms of each element on the reactant (left of arrow) as well as the product side (right of arrow).
The given equation is:
\[{\text{Mg}} + HCl \to MgC{l_2} + {H_2}\]
Now, the reactant side contains three different elements namely magnesium, hydrogen and chlorine. Count the number of atoms of these elements on the reactant as well as product side:
1.Reactant side
\[Mg = 1\]
\[H = 1\]
\[Cl = 1\]
2.Product side
\[Mg = 1\]
\[H = 2\]
\[Cl = 2\]
The number of hydrogen and chlorine atoms are unequal on both sides of the reaction, therefore the given equation is not balanced.
On multiplying the \[HCl\] molecule by two, the equation becomes balanced and can be written as follows:
\[{\text{Mg}} + 2HCl \to MgC{l_2} + {H_2}\]

Note:
The method of counting the number of atoms is an alternative to counting the atomic masses of elements on each side. Like the number of atoms, the total mass of the reactants should also be equal to the mass of products in a balanced reaction. The stoichiometric numbers of each component of the reaction should be included.