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Liquid helium is a physical state of helium, at very low temperatures if it is at standard atmospheric pressures. Liquid helium may show superfluidity.
事实速览 液氦, 识别 ...
液氦 | |
---|---|
IUPAC名 Liquid helium 液氦 | |
英文名 | Liquid helium |
识别 | |
CAS号 | 7440-59-7 ? |
PubChem | 23987 |
性质 | |
化学式 | He |
摩尔质量 | 4.0023 g·mol⁻¹ |
密度 | 0.125 g/cm3(液体) |
熔点 | (at 2.5 MPa) 0.95 K,−272.20 °C,−457.96 °F |
沸点 | 4.222 K,−268.928 °C,−452.070 °F |
危险性 | |
NFPA 704 | |
若非注明,所有数据均出自标准状态(25 ℃,100 kPa)下。 |
关闭
At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temperature of −269 °C (about 4 K or −452.2 °F). Its boiling point and critical point depend on which isotope of helium is present: the common isotope helium-4 or the rare isotope helium-3. These are the only two stable isotopes of helium. See the table below for the values of these physical quantities. The density of liquid helium-4 at its boiling point and a pressure of one atmosphere (101.3 kilopascals) is about 0.125 grams per cm3, or about 1/8th the density of liquid water.[1]