A balanced equation demonstrates the conservation of mass by having the same number of each type of atom on both sides of the arrow.
Consider the balanced equation for the combustion of methane.
##”CH”_4 + “2O”_2 → “CO”_2 + “2H”_2″O”##
All balanced must have the same number of each type of atom on both sides of the arrow.
In this equation, we have 1 ##”C”## atom, 4 ##”H”## atoms, and 4 ##”O”## atoms on each side of the arrow.
The number of atoms does not change, so the total mass of all the atoms is the same before and after the reaction. Mass is conserved.
Here is a video that discusses the importance of balancing a chemical equation.
Video from: Noel Pauller
