Thermochemical Relations for Water at High Temperatures and Pressures

A compilation of the equations and data necessary to determine the equations of state and equilibrium composition of a dense mixture of chemically reacting gases. Emphasis is on the thermodynamic regions that could be attained by this mixture upon subjecting water to a nuclear burst. At present, there are no adequate experimental data to explain the thermodynamic equilibrium properties of water at very high pressure and temperature, and no reliable methods exist to determine the correct functional forms for mixtures of polar and nonpolar molecules, ions, and free radicals at close separations and high temperatures. Using the approach of chemical thermodynamics, the study presents methods for determining the pressure, internal energy, entropy, Helmholtz free energy, chemical potential, and composition as functions of the temperature and volume of the gas mixture. These should be regarded as interpolation procedures that smoothly join results in other regions that are covered by experimental data or adequate physical theories.