Question

How would you balance the following equation:
\[Mg\left( s \right) + {O_2}\left( g \right) \to MgO\left( s \right)\].

Answer 1

Hint: First we know the law of conservation of mass states that mass is neither created nor destroyed by chemical reactions or physical transformations in an isolated (closed) system. To balance the chemical reaction, first consider the unbalanced equation to show the reactants and products. Then we need to add coefficients (the numbers in front of the formulas) so that the number of atoms of each element is the same on both sides of the chemical equation.

Complete answer:
According to the law of conservation of mass, the mass of the products must equal the mass of the reactants in a chemical reaction. So, chemical equations must be balanced, to satisfy the law of conservation of matter. Balanced chemical equations have the same number and type of each atom on both sides of the equation.
Given unbalanced chemical equation is
\[Mg\left( s \right) + {O_2}\left( g \right) \to MgO\left( s \right)\]--(1)
In the equation (1), the number of \[O\] atoms in the reactants and products are \[2\]and \[1\] respectively. To make the number of atoms the same on both the reactants and products sides we need to multiply \[Mg\]( Magnesium) and \[MgO\](Magnesium oxide) by \[2\]. Then the number of atoms in the reactants and products become the same.
Then the balanced chemical equation is
\[2Mg\left( s \right) + {O_2}\left( g \right) \to 2MgO\left( s \right)\].

Note:
Chemical equation or reaction is defined as, representation of a chemical reaction in terms of symbols and chemical formula of the reactants and products taking part in the reaction. The five basic types of chemical reactions are combination, decomposition, single-replacement, double-replacement, and combustion. Also note that the coefficients in a balanced equation must be the simplest whole number ratio.