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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).
However, Kamerlingh Onnes, his rival, was the first to liquefy helium, in 1908, using several precooling stages and the Hampson–Linde cycle. He lowered the temperature to the boiling point of helium −269 °C (−452.20 °F; 4.15 K). By reducing the pressure of the liquid helium, he achieved an even lower temperature, near 1.5 K.
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]
The combination of helium’s extremely low molecular weight and weak interatomic reactions yield interesting properties when helium is cooled below its critical temperature of 5.2 K to form a liquid. Even at absolute zero (0K), helium does not condense to form a solid under ambient pressure.
Nitrogen is a liquid under −195.8 °C (77.3 K).. In physics, cryogenics is the production and behaviour of materials at very low temperatures.. The 13th International Institute of Refrigeration's (IIR) International Congress of Refrigeration (held in Washington, DC in 1971) endorsed a universal definition of "cryogenics" and "cryogenic" by accepting a threshold of 120 K (−153 °C) to ...
This condition is known as absolute zero and it forms the basis for the Kelvin temperature scale, which measures the temperature above absolute zero. Zero degrees Celsius (°C) coincides with 273 Kelvin. At absolute zero most elements become a solid, but not all behave as predictably as this; for instance, helium becomes a highly unusual liquid ...
-252 °C: 2 He helium; use: 4.222 K: −268.928 °C: −452.07 °F ... Values are in kelvin K and degrees Celsius °C, rounded For the equivalent in degrees ...
2 He helium; use (T/K) 3 4 CRC.b (T/°C) -270.6 ... SMI.c,f: solid, 946..1083 °C: log (P/Pa ... refers to temperature in Kelvin (K) (P/Pa) refers to pressure in ...