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Conservation of Mass: The Fundamental Law

The conservation of mass states that the total mass in a closed system remains constant—matter cannot be created or destroyed during a chemical reaction. In practice, the sum of the masses of reactants equals the sum of the masses of products, and the total number of atoms for each element is identical on both sides of the equation.

Historical Roots

In 1789 Antoine Lavoisier formalized the principle after meticulous experiments, establishing it as a cornerstone of modern chemistry. Though earlier Greek philosophers such as Anaxagoras noted that matter is merely rearranged, Lavoisier’s quantitative work earned him the credit for discovering the law.

Practical Steps for Balancing Equations

1. Count the atoms of each element on both sides.
2. If the counts differ, introduce integer coefficients in front of the molecular formulas—coefficients must be whole numbers and cannot alter the chemical formulas.
3. Adjust the coefficients iteratively until every element balances.

Example: Ammonia Synthesis

Unbalanced: N₂ + H₂ → NH₃
Balancing process: Add a coefficient of 3 to H₂ and 2 to NH₃ to achieve N₂ + 3H₂ → 2NH₃. Every element now appears in equal numbers on both sides.

For more details, visit Wikipedia: Conservation of mass.