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Helium is the least water-soluble monatomic gas, [96] and one of the least water-soluble of any gas (CF 4, SF 6, and C 4 F 8 have lower mole fraction solubilities: 0.3802, 0.4394, and 0.2372 x 2 /10 −5, respectively, versus helium's 0.70797 x 2 /10 −5), [97] and helium's index of refraction is closer to unity than that of any other gas. [98]
Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures.Liquid helium may show superfluidity.. At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temperature of −269 °C (−452.20 °F; 4.15 K).
2 He helium; use: 4.222 K: ... all values refer to the normal boiling point at standard ... "Estimation Chemical Form Boiling Point Elementary Astatine by Radio Gas ...
2 He helium; use: 0.0829 CRC: 0.08 LNG: 0.0829 WEL: 0.083 3 ... Values refer to the enthalpy change in the conversion of liquid to gas at the boiling point (normal ...
This list is sorted by boiling point of gases in ascending order, ... Helium-3: 3 He −269.96 N/A 3 14762-55-1 ... F is a gas but decomposes over several hours ...
At ambient pressure the boiling point of liquefied helium is 4.22 K (−268.93 °C). Below 2.17 K liquid 4 He becomes a superfluid (Nobel Prize 1978, Pyotr Kapitsa) and shows characteristic properties such as heat conduction through second sound, zero viscosity and the fountain effect among others.
Boca Raton, Florida, 2003; Section 6, Fluid Properties; Critical Constants. Also agrees with Celsius values from Section 4: Properties of the Elements and Inorganic Compounds, Melting, Boiling, Triple, and Critical Point Temperatures of the Elements Estimated accuracy for Tc and Pc is indicated by the number of digits.
Helium is the smallest and the lightest noble gas and one of the most unreactive elements, so it was commonly considered that helium compounds cannot exist at all, or at least under normal conditions. [1] Helium's first ionization energy of 24.57 eV is the highest of any element. [2]