The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. This principle can be illustrated with the equation of a simple combustion reaction, such as the combustion of methane (\( CH_4 \)):
\[ CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O \]
In this equation, if you count the number of atoms of each element before and after the reaction, you will find that they are the same:
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On the left side:
- Carbon (C) = 1
- Hydrogen (H) = 4
- Oxygen (O) = 4 (from \( 2O_2 \))
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On the right side:
- Carbon (C) = 1 (from \( CO_2 \))
- Hydrogen (H) = 4 (from \( 2H_2O \))
- Oxygen (O) = 4 (2 from \( CO_2 \) and 2 from \( 2H_2O \))
This demonstrates that the total mass of the reactants (on the left) equals the total mass of the products (on the right), thereby illustrating the law of conservation of mass.