Mass is conserved in this reaction because the total mass of the reactants (methane and oxygen) is equal to the total mass of the products (carbon dioxide and water).
How is the mass conserved?
The model above shows that one molecule of methane (CH4) reacts with two molecules of oxygen (O2) to produce one molecule of carbon dioxide (CO2) and two molecules of water (H2O). This is a balanced chemical equation, which means that the number of atoms of each element is the same on both sides of the equation.
Mass is conserved in this reaction because the total mass of the reactants (methane and oxygen) is equal to the total mass of the products (carbon dioxide and water). The Law of Conservation of Mass states that in any chemical reaction, the total mass of the reactants is equal to the total mass of the products. This means that the total number of atoms of each element is the same on both sides of the equation, and therefore the total mass is conserved.