Chemical Reactions: Videos & Practice Problems

Chemical reactions are fundamental processes that involve the making and breaking of chemical bonds, resulting in changes in matter. Each chemical reaction consists of two main components: reactants and products. Reactants are the starting materials, akin to ingredients in a recipe, while products are the substances formed at the end of the reaction.

In a typical representation of a chemical reaction, reactants are displayed on the left side of a reaction arrow, indicating their role as the initial substances. Conversely, products are shown on the right side, signifying the outcome of the reaction. This can be visualized as building blocks being broken down into smaller pieces on the left, which then come together to form a more complex structure on the right.

Understanding the distinction between reactants and products is crucial as it lays the groundwork for exploring various types of chemical reactions in greater detail. As you progress through your studies, you will have opportunities to practice identifying and working with these components in different chemical contexts.

Chemical reactions can be categorized into two main types based on their energy requirements: endergonic and exergonic reactions. Understanding these categories is essential for grasping how energy is utilized and transformed in chemical processes.

Endergonic reactions require an input of energy to proceed. The term "endergonic" can be broken down to highlight this need: "en" suggests energy entering the reaction. In these reactions, smaller, less complex reactants combine to form larger, more structured products. This process necessitates energy, which is absorbed from the surroundings, resulting in products that possess higher potential energy than the reactants. Graphically, this is represented by a curve where the potential energy increases as the reaction progresses, indicating that energy is being added to the system.

Conversely, exergonic reactions release energy into the environment. The prefix "ex" signifies energy exiting the reaction. In these cases, the reaction starts with larger, more complex molecules that break down into smaller components. As the reaction occurs, energy is released, leading to products that have lower potential energy compared to the reactants. This is illustrated in a graph where the energy decreases as the reaction progresses, demonstrating that energy is leaving the system.

Both endergonic and exergonic reactions play crucial roles in biological systems, allowing cells to build complex molecules and break them down for energy. Recognizing the differences between these two types of reactions is fundamental for understanding metabolic processes and energy flow in living organisms.