What is the law of conservation of mass, and who discovered it?

Chemical reactions are fundamental processes where substances, known as reactants, are transformed into different substances called products. Imagine baking a cake: you start with ingredients like flour, sugar, and eggs (the reactants), and end up with a delicious cake (the product). Similarly, in chemical reactions, bonds between atoms are broken and new ones are formed, resulting in new substances. Each of these substances has a characteristic mass, and during a chemical reaction, these masses undergo a transformation. The arrangement of atoms changes, but interestingly, the total mass remains the same. This leads us to the intriguing concept of mass conservation.

The principle of mass conservation is a scientific axiom stating that mass cannot be created or destroyed in an isolated system through physical changes or chemical reactions. It's like saying if you cut a pie into pieces, the pieces put together still weigh as much as the original pie. During chemical reactions, atoms are rearranged into new configurations but their total mass is conserved. The same number of each type of atom exists before and after the reaction, they're just arranged differently. This persistent mass total is a core concept in chemistry and is used for calculating the yields of reactions and balancing chemical equations. The law is a crucial pillar for stoichiometry, which deals with the relative quantities of reactants and products in chemical reactions.

The law of conservation of mass was pioneered by Antoine Lavoisier, often referred to as the 'father of modern chemistry.' In the late 18th century, Lavoisier conducted numerous experiments, meticulously measuring the mass of substances before and after chemical reactions. He observed that in a closed environment, no mass was lost or gained. His careful approach to experimentation and his insistence on precise measurement revolutionized the field of chemistry. Lavoisier's work not only led to the law of mass conservation but also helped to debunk phlogiston theory, an erroneous theory that postulated a fire-like element released during combustion.

A closed system in chemistry is a type of system that does not exchange matter with the surrounding environment, although it can exchange energy. Consider it as a sealed box where nothing gets in or out, but the temperature inside can change. This concept is essential for the law of conservation of mass because it provides the controlled environment necessary to ensure that no additional mass is introduced or lost during a reaction. In the real world, perfectly closed systems are an idealization, but they are a useful concept when applying the law of conservation of mass in order to understand and predict the outcomes of chemical reactions without outside interference.