How does the law of conservation of mass apply to chemical reactions?

The law of conservation of mass states that in a chemical reaction, the total mass of the reactants equals the total mass of the products.

In more detail, the law of conservation of mass, also known as the principle of mass conservation, is a fundamental concept in chemistry. It was first formulated by Antoine Lavoisier in the late 18th century. This law states that matter cannot be created or destroyed in an isolated system. In the context of a chemical reaction, this means that the total mass of the substances involved in the reaction remains constant, regardless of the nature of the substances themselves, the process by which they are transformed, or the products that result.

For example, if you were to react hydrogen gas with oxygen gas to produce water, the total mass of the hydrogen and oxygen you started with would be exactly the same as the total mass of the water you ended up with. This is because during the reaction, the hydrogen and oxygen atoms are not destroyed or created, but simply rearranged to form water molecules.

This principle is crucial in balancing chemical equations. In a balanced chemical equation, the number of atoms of each element on the reactant side of the equation must equal the number of atoms of that element on the product side. This is because, according to the law of conservation of mass, the total mass before and after the reaction must be the same.

However, it's important to note that this law applies strictly to closed systems, where no matter is allowed to enter or leave the system. In an open system, the mass of the reactants and products may not be equal due to the loss or gain of matter to the surroundings.

In summary, the law of conservation of mass is a fundamental principle in chemistry that governs the way atoms are rearranged during chemical reactions. It ensures that no matter is lost or gained during a reaction, maintaining a constant total mass.