Enthalpieanhänge

Enthalpieanhänge are appendices found in thermodynamics, physical chemistry, or chemical engineering texts and reports that compile enthalpy-related data. They serve as a reference resource rather than a theoretical concept, providing numerical values and formulas needed to perform energy calculations.

Typically, enthalpieanhänge include standard enthalpies of formation (ΔHf°), enthalpies of reactions (ΔHr°) at a reference pressure, and enthalpies of phase transitions such as fusion and vaporization. They also present temperature-dependent information for heat capacities (Cp) and enthalpy changes over ranges of temperature, often in tabulated form or via agreed correlations (for example constant Cp approximations, Shomate equations, or NASA polynomials). Data may be given per mole or per kilogram and usually referenced to standard conditions, commonly 1 bar and 298 K.

These appendices are used to compute energy balances, design and optimization of chemical processes, and simulations where accurate enthalpy data are required. They help determine total heat requirements or yields, track phase changes, and convert between enthalpy at different temperatures. In addition to tabulated values, many enthalpieanhänge discuss methodological notes, uncertainty, and the validity range of the data.

Reliability relies on sourcing from established databases and literature, such as NIST, JANAF tables, or peer‑reviewed compilations. Practitioners must pay attention to units, reference states, and the substance’s phase and pressure since enthalpy values can vary with conditions. When using enthalpieanhänge, it is common practice to ensure consistency of data sources and to verify applicability to the specific process conditions.