Question

A student balanced the chemical equation Mg + O2 →MgO by writing Mg + O2 → MgO2. Was the equation balanced correctly? Explain your answer. If the equation was not balanced correctly, write the correctly balanced equation.

Answer 1

Explanation:

Charges on both magnesium and oxygen is 2. Though opposite in sign, they have equal charges so, both of them will be cancelled by each other.

As a result, formula of magnesium oxide is MgO and not $MgO_{2}$.

The student write the equation as $Mg + O_2 \rightarrow MgO_2$, it is not correct.

Therefore, given equation will be balanced as follows.

          $2Mg + O_{2} \rightarrow 2MgO$

Since, number of atoms on both reactant and product side are equal. Hence, this equation is completely balanced.