What has the lowest freezing point?

Science

Michael Anissimov

Last Modified Date: October 12, 2022

Michael Anissimov Last Modified Date: October 12, 2022

The material with the lowest freezing point is helium. Under typical pressures, it does not freeze at all, even at temperatures approaching absolute zero. The reasons why are dictated by quantum mechanics: the zero point energy of a helium system is too great to allow freezing. The zero point energy is the minimum energy a particle or system always has, no matter what. Helium is the only substance that does not have a freezing point under ambient pressure, no matter the temperature.

A freezing point for helium only exists under at least 25 atmospheres of pressure and a temperature of 1.15 K. These conditions have been created in a laboratory through evaporative cooling. The result is a colorless, highly compressible solid that is practically invisible. Solid helium is so difficult to see that layers of styrofoam are used just to tell where it is. The density of solid helium itself is only 66 times greater than air. By comparison, water is 1000 times more dense than air.

Helium has the lowest freezing point.

Helium was first liquefied in 1908 by Dutch physicist Heike Onnes, who cooled it to 1 degree Kelvin. Much to his surprise, further cooling did not cause it to reach its freezing point. It wasn’t until 18 years later, in 1926, that his student, Williem Keesom, was able to solidify helium by cooling it in a pressure chamber. Today, the liquefaction of helium is a vital step in extracting it from the earth and storing it.

Liquid helium is often used as a cryogenic cooling agent when liquid nitrogen isn’t enough. It must be kept under continuous high pressure and low temperature, otherwise it quickly expands and transitions to a gas. Solid helium does not have any practical applications outside of scientific research.

Some of helium’s most unusual properties can be coaxed out at temperatures close to absolute zero. At such temperatures, helium behaves as a superfluid, meaning it flows with zero measurable viscosity. It also has a tendency to creep up the walls of a container it is held in.

Michael is a longtime AllTheScience contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Michael Anissimov

The chemical element with the highest melting point is tungsten, at 3695 K (3422 °C, 6191 °F). The often-cited carbon does not melt at ambient pressure but sublimates at about 4000 K; a liquid phase only exists above pressures of 10 MPa and estimated 4300–4700 K. Tantalum hafnium carbide (Ta4HfC5) is a refractory compound with a very high melting point of 4488 K (4215 °C, 7619 °F).[1] At the other end of the scale, helium does not freeze at all at normal pressure, even at absolute zero.

https://en.wikipedia.org/wiki/Melting_point

Aug 02 2006, 3:06 PM

right, but liquid helium freezes at what temperature?
I knew Hydrogen froze at less than one degree above 0k (absolute zero) but what about Helium, what's its freezing point?

Aug 02 2006, 3:58 PM

Helium is the most difficult of all gases to liquefy and is impossible to solidify at atmospheric pressure. These properties make liquid helium extremely useful as a refrigerant and for experimental work in producing and measuring temperatures close to absolute zero. Liquid helium can be cooled almost to absolute zero at normal pressure by rapid removal of the vapor above the liquid. At a temperature slightly above absolute zero, it is transformed into helium II, also called superfluid helium, a liquid with unique physical properties. It has no freezing point, and its viscosity is apparently zero; it passes readily through minute cracks and pores and will even creep up the sides and over the lip of a container. Helium-3, the lighter helium isotope of mass 3, which has an even lower boiling point than ordinary helium, exhibits markedly different properties when liquefied. See Superfluidity.
[encarta.msn.com/encyclopedia_761562418/Helium.html]

http://www.uky.edu/~garose/helium

Response last updated by gtho4 on Aug 25 2016.

Aug 02 2006, 4:07 PM