## At same temperature, oxygen is more soluble in water than

A. Rahbari, A. Rahbari, A. Rahbari, A (TU Delft Engineering Thermodynamics) Brenkman, Jeroen (Shell Global Solutions International B.V.) Hens, R. (TU Delft Engineering Thermodynamics) Ramdin, M. (TU Delft Engineering Thermodynamics) van den Broeke, L.J.P. (TU Delft Engineering Thermodynamics) Rogier Schoon, Rogier Schoon, Rogier Schoon, Ro (Shell Global Solutions International B.V.) R.A.W.M. Henkes, R.A.W.M. Henkes, R.A.W.M (TU Delft Fluid Mechanics; Shell Global Solutions International B.V.) O. Moultos (TU Delft Engineering Thermodynamics) T.J.H. Vlugt (TU Delft Engineering Thermodynamics)

## Henry’s law explained – gas solubility & partial pressure

The molarity (moles/liter (M) or milimoles/L mM) of hydrogen gas (H2) is commonly stated in parts per million (ppm), parts per billion (ppb), or miligrams per liter (mg/L). 1 ppm is roughly equivalent to 1 mg/L in dilute amounts, and the terms are often interchanged. Since molecular hydrogen has a molar mass of about 2 mg/milimole, 1 mg is about the same as 0.5 moles, so 1 ppm = 1 mg/L =0.5 mM.
Hydrogen gas (H2) concentration in ordinary water (tap, bottled, filtered, etc.) is around 8.65 x 10-7 mg/L. In other words, the amount of H2 is less than one eighth of a milligram. As a result, H2 has no medicinal benefit in normal filtered water at such low concentrations. The amounts of hydrogen gas dissolved in water used in studies vary from 0.5 mg/L to 1.6 mg/L, with the majority of them using a concentration around 1.6 mg/L. (0.8 mM).
The concentration at “saturation” is 1.6 mg/L (1.6 ppm or 0.8 mM) in scientific literature and that is what the concentration would be if only hydrogen gas was present at a pressure equal to the pressure at sea level, which is 760 mm-mercury (760 torr, 101.325 kPa, 1.01325 barr, or 14.69595 psi,) therefore equal to one atmosphere (atm). The solubility of different gases in water is explained below, with an emphasis on the solubility of molecular hydrogen.

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### Solubility of gases

In normal conditions, 30-60 ml/kg of hydrogen is present in the coolant of water-water reactors as a result of radiolytic decomposition of water and chemical additives (hydrazine and ammonia) and saturation of the make-up water of the first loop with free hydrogen to prevent radiolysis. As hydrogen is released from the water, it is free to collect in metal micropores, resulting in hydrogen embrittlement; gas accumulates in stagnant areas, degrading heat transfer in the first loop and making the reactor and the whole reactor loop more difficult to use. It is important to know the limiting solubility of hydrogen in water at various temperatures and pressures, as well as the related theoretical dependences, in order to determine the amount of free hydrogen and hydrogen dissolved in water in different elements of the first loop. The experimental data on hydrogen solubility in water is ad hoc and does not cover the parameter ranges of modern nuclear power plants (P = 10-30 MPa, T = 260-370C). As a result, the aim of this research is to develop a well-founded method for calculating hydrogen’s limiting solubility in water and, using that method, to compile tables of hydrogen’s limiting solubility in water at pressures 0.1-50 MPa and temperatures 0-370C.

### Which molecule is most soluble in water?

The American Astronomical Society (AAS), based in Washington, DC, was founded in 1899 and is the largest professional astronomy organization in North America. Its approximately 7,000 members include physicists, mathematicians, geologists, engineers, and others with scientific and educational interests in the wide range of topics that make up contemporary astronomy. The American Astronomical Society’s mission is to advance and disseminate humanity’s scientific understanding of the cosmos. https://aas.org/ We investigate whether water ice is stable in the cores of giant planets, or whether it dissolves into the layer of metallic hydrogen above, using ab initio simulations. The ice-hydrogen interface is thermodynamically unstable at temperatures above approximately 3000 K, well below the temperature of the core-mantle boundaries in Jupiter and Saturn, according to Gibbs free energy measurements for pressures between 10 and 40 Mbar. This suggests that the breakdown of core material into the fluid layers of giant planets is thermodynamically advantageous, and that further research into the degree of core erosion is required.