Chemical reactions are fundamental processes constantly occurring around and within us, shaping the world in countless ways. These transformations underpin everything from the simplest biological functions, like digestion, to complex industrial manufacturing processes. They involve substances interacting and changing to form new materials with different properties. Understanding the basic components of these reactions helps to demystify how these changes take place.
What Are Reactants?
Reactants are the initial substances present at the beginning of a chemical reaction. They are the raw materials that undergo a chemical change, meaning their original chemical identities are altered. As the reaction proceeds, these starting materials are consumed. In a chemical equation, which is a symbolic representation of a chemical reaction, reactants are conventionally written on the left side of an arrow. For instance, if substances A and B combine to form C, A and B are the reactants.
The properties of reactants, such as their physical state (solid, liquid, gas, or aqueous), can influence how a reaction proceeds. The number of atoms for each element in the reactants must be equal to the number of atoms for those elements in the products in a balanced chemical equation, following the principle of mass conservation. Reactants are distinct from reagents, which are substances added to cause a reaction but are not always consumed.
From Reactants to Products
The transformation of reactants into products is the essence of a chemical reaction. During this process, the chemical bonds within the reactant molecules break, and new bonds form to create entirely different substances, known as products. This change results in the products having chemical properties distinct from the original reactants.
This conversion is not merely a physical change, like melting ice, but a fundamental alteration of the substances’ chemical composition. The conditions under which a reaction occurs, such as temperature or pressure, can influence how reactants are converted and what products are formed.
Reactants in Everyday Life
Chemical reactions, and thus reactants, are integral to many everyday phenomena. In the familiar process of burning wood, the wood and oxygen from the air act as reactants. These combine to produce new substances like ash, carbon dioxide, and water vapor. Another common example is the reaction between baking soda (sodium bicarbonate) and vinegar (acetic acid). Here, baking soda and vinegar are the reactants that produce carbon dioxide gas, which causes bubbling.
Photosynthesis, a process fundamental to life on Earth, also involves specific reactants. Plants use carbon dioxide from the atmosphere and water from the soil as reactants. With the energy from sunlight, these reactants are transformed into glucose (a sugar, which is the plant’s food) and oxygen. Even within the human body, digestion involves numerous chemical reactions where food molecules act as reactants, broken down by enzymes into simpler substances the body can absorb.