What is internal energy?

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1. Internal energy is a concept in thermodynamics that refers to the total energy contained within a system.
2. It includes all forms of energy present in the system, such as kinetic energy of particles, potential energy due to intermolecular forces, and chemical energy stored in bonds.
3. Internal energy is a state function, meaning it depends only on the current state of the system, not on how the system reached that state.
4. The change in internal energy (ΔU) of a system can be calculated using the first law of thermodynamics: ΔU = Q - W, where Q is the heat added to the system and W is the work done by the system.
5. Understanding internal energy is crucial for analyzing energy changes in chemical reactions and physical processes.

Key Concepts

Internal Energy

Internal energy is the total energy contained within a system, encompassing both kinetic and potential energy at the molecular level. It reflects the energy associated with the random motion of particles and the interactions between them. Changes in internal energy can occur due to heat transfer or work done on or by the system.

First Law of Thermodynamics

The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another. This principle implies that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system. It establishes a fundamental relationship between heat, work, and internal energy.

State Functions

State functions are properties that depend only on the current state of a system, not on the path taken to reach that state. Internal energy is a state function, meaning its value is determined solely by the system's current conditions, such as temperature and pressure, rather than how the system arrived at those conditions. This characteristic is crucial for understanding thermodynamic processes.