The density of helium
Helium is the most abundant element in the universe after hydrogen. However, it is not an ordinary substance, but has many special features. The density in different states of aggregation is also extremely remarkable.
Density of helium in a gaseous state
First of all, helium is a noble gas that is colorless, odorless and neutral in terms of taste. It is one of the non-toxic gases and is known as the most inert element known to date.
- If standard conditions prevail, the helium is to be rated as an almost ideal gas. It is almost always in the atomic state, is a very good insulator with respect to electricity and has a water solubility which is lower than that of all other gases.
- After hydrogen, it is the gas with the lowest density, but at the same time has the lowest boiling and melting points of all elements.
The density in the gaseous state is 0.1785 kg · m−3. Helium has around seven times less mass per unit volume than oxygen.
More about liquid helium
- To obtain gaseous helium, many conditions must be met. The Joule-Thomson inversion temperature must first be reached, since before that it only heats up when it expands. This point is for helium at a density of 0.0696 g / cm
3 and the pressure of 2.27 bar
respectively. reached a temperature of −267.95 ° C. - It forms a liquid without color between its lambda point, which is classified at 2.1768 K, and its boiling point at 4.21 K. As soon as the temperature drops below the lambda point, which says that within the present superfluid fluid the internal friction is zero, so the substance exhibits remarkable Properties on.
- Boiling the liquid substance, as would be possible with water, for example, does not work. Instead, liquid helium evaporates immediately when the boiling point is reached. At this point there is a density of approx. 0.125 kg / l.
How do gases behave when heated? - Useful information
In chemistry classes, experiments are always carried out to determine the behavior of substances ...
The solid state of helium
- If normal pressure prevails, helium cannot become a solid. This requires around 25 times the pressure (2.5MPa) and also a temperature of less than 1.5 Kelvin.
- The resulting solidified material is visually almost indistinguishable from the liquid state, the refractive indices are almost the same.
The Mickey Mouse voice that you get when you inhale helium can also be compared with its special Explain properties: Sound waves can move twice as fast in pure helium as in Air.
