To balance the equation, we need to ensure that the same number of each type of atom appears on both sides of the equation. In this case, we have one magnesium atom, two chlorine atoms, and six oxygen atoms on the left side (reactants), and one magnesium atom, two chlorine atoms, and 2 oxygen atoms on the right side (products).
To balance the number of chlorine atoms, we need to ensure that there are two chlorine atoms on both sides of the equation. This is achieved by placing a coefficient of 1 in front of Mg(ClO3)2 and a coefficient of 1 in front of MgCl2:
1Mg(ClO3)2 → 1MgCl2 + _O2
- note coefficients of one do not need to be emphasized and can be left out
Now we have two chlorine atoms on both sides of the equation, but the number of oxygen atoms is not balanced. We need three oxygen atoms on the right side of the equation to balance the six oxygen atoms on the left side. This is achieved by placing a coefficient of 3 in front of O2:
Mg(ClO3)2 → MgCl2 + 3O2
Now the equation is balanced, as there are one magnesium atom, two chlorine atoms, and six oxygen atoms on both sides of the equation. Following the law of conservation of mass which states that mass can not be created nor destroyed in a chemical reaction.