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Why must chemical equations have equal numbers of each type of atom on both sides?
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chemical reaction
Log burning in a fire. Burning wood is an example of a chemical reaction in which wood in the presence of heat and oxygen is transformed into carbon dioxide, water vapor, and ash.
Chemical equations must have equal numbers of each type of atom on both sides because of the law of conservation of mass. This fundamental principle states that matter—including atoms and molecules—cannot be created or destroyed during a chemical reaction.123
In any chemical process, the constituent atoms of the reactants are simply rearranged to form new substances, known as products. Because no atoms are lost or gained, the total mass of the reactants must equal the total mass of the products. Consequently, a balanced chemical equation is required to accurately represent this reality, ensuring that the same number of atoms of each element appears on both sides of the equation.43