In which law is the concept of conservation of energy central?

The First Law of Thermodynamics is fundamentally centered around the concept of conservation of energy. This law states that energy cannot be created or destroyed; rather, it can only be transformed from one form to another or transferred between systems. In a closed system, the total amount of energy remains constant, although it may change forms—such as from chemical energy to thermal energy or from mechanical energy to electrical energy.

This principle has profound implications for understanding energy transfer and transformation in various physical processes. For example, when a substance undergoes a phase change, the energy added or removed is accounted for by the change in internal energy of that system. The First Law is often expressed mathematically as ΔU = Q - W, where ΔU is the change in internal energy, Q is the heat added to the system, and W is the work done by the system.

Recognizing that energy is conserved in all processes is essential for analyzing and predicting the behavior of systems in thermodynamics. This focus on energy conservation distinguishes the First Law from the other laws of thermodynamics, which address different aspects of thermal processes and energy distribution in systems.