Entalpiaváltozás

Entalpiaváltozás, often referred to as enthalpy change, is a thermodynamic quantity that represents the total heat content of a system. In chemistry, it is specifically used to describe the heat absorbed or released during a chemical reaction at constant pressure. The symbol for enthalpy change is ΔH. A positive ΔH indicates an endothermic process, where the system absorbs heat from its surroundings. Conversely, a negative ΔH signifies an exothermic process, where the system releases heat into its surroundings.

The enthalpy change is a state function, meaning it depends only on the initial and final states of the system, not on the path taken to get there. This allows for the calculation of enthalpy changes for complex reactions by summing the enthalpy changes of simpler, known reactions (Hess's Law). Enthalpy change is measured in units of energy, typically joules (J) or kilojoules (kJ). It is a crucial concept for understanding energy transformations in chemical and physical processes, predicting the feasibility of reactions, and designing chemical processes. For instance, knowing the enthalpy change of a combustion reaction is vital for determining the amount of heat energy that can be produced.