entalpiával

Entalpia (H) is a thermodynamic property that represents the heat content of a system at constant pressure. It is defined as the sum of the internal energy (U) and the product of pressure and volume (pV): H = U + pV. Because it is a state function, its value depends only on the current state of the system, not on how that state was reached. For many practical purposes, especially in chemistry and engineering, entalpia is more convenient than internal energy because changes at constant pressure are directly related to heat exchange.

The change in entalpia for a process at constant pressure equals the heat added or removed: ΔH = q_p. This makes entalpia a central concept in calorimetry and in the analysis of chemical reactions. Enthalpy can also be expressed in molar terms (per mole) or gravimetric terms (per kilogram). The temperature dependence of entalpia is described by the molar heat capacity at constant pressure, Cp, through dH = Cp dT. Thus, entalpia varies with temperature, phase, and composition of the system.

Common components of entalpia data include standard enthalpies of formation, enthalpies of reaction, and enthalpies of phase transitions such as fusion and vaporization. These values enable Hess’s law calculations to determine the enthalpy change of complex processes from known constituent data. Enthalpy data are typically determined experimentally via calorimetry or derived from thermodynamic tables.

In Hungarian scientific language, the word entalpia is used with various grammatical forms, for example entalpiával meaning “with enthalpy.” This instrumental form appears in phrases that address heat content or enthalpy-related calculations in a given context.