1. Atoms are not created or destroyed: Chemical reactions involve the rearrangement of atoms, not their creation or destruction. Atoms simply change their bonding partners.
2. Rearrangement of atoms: In a reaction, bonds between atoms in the reactants are broken, and new bonds are formed to create the products. This rearrangement doesn't change the total number of atoms involved.
3. Conservation of mass: Because the number of atoms remains constant throughout the reaction, the total mass of the reactants must equal the total mass of the products. This is because the mass of each atom remains the same, regardless of its bonding arrangement.
Example:
Consider the simple reaction of hydrogen gas (H₂) reacting with oxygen gas (O₂) to form water (H₂O):
2H₂ + O₂ → 2H₂O
* Reactants: 4 hydrogen atoms and 2 oxygen atoms
* Products: 4 hydrogen atoms and 2 oxygen atoms
The number of atoms of each element remains the same on both sides of the equation. Therefore, the total mass of the reactants (hydrogen and oxygen) equals the total mass of the product (water), demonstrating the Law of Conservation of Mass.
Important Note: This principle applies to closed systems where there is no exchange of matter with the surroundings. In open systems, mass can be lost or gained due to factors like evaporation or the introduction of new substances.
