A chemical reaction is a process that transforms one set of chemical substances into another, fundamentally changing their identity. This transformation involves the breaking of existing bonds and the formation of new bonds to create different substances. The total amount of matter involved remains constant, adhering to the Law of Conservation of Mass. This means atoms are neither created nor destroyed, but simply rearranged into new combinations during the process. The result is new materials with distinct properties from those that started the reaction.
The Core Components of a Chemical Reaction
Any chemical reaction involves two fundamental categories of materials. The substances present at the beginning of the process are called the reactants. These starting materials are consumed as the reaction progresses, providing the atoms that will be restructured into new forms.
Reactants initiate the chemical change, often requiring specific conditions like heat, light, or a catalyst to begin. As the atoms within the reactants rearrange, their original chemical identities are lost, resulting in the formation of new substances.
Defining the Result: What Products Are
The substances that are produced as a result of a chemical reaction are collectively referred to as the products. Products are the end materials of the process, possessing entirely different chemical and physical properties than the reactants from which they were formed. For example, the reaction between zinc and sulfur yields the product zinc sulfide, a white compound distinct from its silvery and yellow components.
A common everyday example is the rusting of iron, where the metal reacts with oxygen to form iron oxide, a reddish-orange compound. The soft, conductive metal changes into a brittle, non-conductive ceramic, demonstrating a complete change in properties. Similarly, mixing baking soda and vinegar produces carbon dioxide gas, a product with a completely different physical state.
Representing Reactions: The Chemical Equation
Scientists use a standardized visual shorthand called a chemical equation to represent the transformation from reactants to products. By convention, the substances on the left side of the equation are the reactants, and the substances on the right side are the products. The two sides are separated by an arrow (->), which is read as “yields” or “forms” and indicates the direction of the chemical change.
For instance, the formation of water shows hydrogen gas and oxygen gas as reactants yielding water as the product. To uphold the Law of Conservation of Mass, the equation must be balanced so the number of atoms of each element is identical on both sides. This balance is achieved by placing whole numbers, known as coefficients, in front of the chemical formulas.