Consider the accompanying energy diagram. (a) Does this diagram represent an increase or decrease in the internal energy of the system?

Key Concepts

Internal Energy

Internal energy is the total energy contained within a system, including kinetic and potential energy of the particles. It is a state function, meaning it depends only on the current state of the system, not on how it got there. Changes in internal energy can indicate whether a reaction is endothermic or exothermic.

Energy Diagrams

Energy diagrams visually represent the energy changes during a chemical reaction. The vertical axis typically shows internal energy, while the horizontal axis represents the progress of the reaction. The difference in energy between reactants and products indicates whether energy is absorbed or released during the reaction.

Exothermic vs. Endothermic Reactions

Exothermic reactions release energy to the surroundings, resulting in a decrease in the internal energy of the system, while endothermic reactions absorb energy, leading to an increase in internal energy. In the context of the provided energy diagram, a downward arrow from reactants to products signifies an exothermic reaction, indicating a decrease in internal energy.