The Behavior of H-2 in Aqueous Fluids under High Temperature and Pressure

The presence of H-2 and H2O in planetary interiors prompts the need for fundamental studies on these compounds under corresponding conditions. Here, we summarize data on H-2 properties In aqueous systems under conditions of high temperature and pressure. We explain how to measure important H-2 fugacities in hydrothermal systems. We present available experimental data and thermodynamic models for H-2 solubility and vapor-liquid partitioning under hydrothermal conditions. In addition, we introduce the fascinating world of H-2-H2O clathrate hydrates under extreme temperatures and pressures. The properties of the H-2-H2O system are well established below the critical point of water (374 degrees C and 22.06 MPa), but far less is known under higher temperatures and pressures, or the effect of salt.