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Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest element and, at standard conditions, is a gas of diatomic molecules with the formula H2, sometimes called dihydrogen, [ 11] but more commonly called hydrogen gas, molecular hydrogen or simply hydrogen. It is colorless, odorless, tasteless, [ 12] non-toxic ...
Md. No. Legend. Values are in kelvin K and degrees Celsius °C, rounded. For the equivalent in degrees Fahrenheit °F, see: Boiling points of the elements (data page) Some values are predictions. Primordial From decay Synthetic Border shows natural occurrence of the element. s-block.
Liquid hydrogen ( H2(l)) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H 2 form. [ 4] To exist as a liquid, H 2 must be cooled below its critical point of 33 K. However, for it to be in a fully liquid state at atmospheric pressure, H 2 needs to be cooled to 20.28 K (−252.87 °C; −423.17 °F). [ 5]
The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [ Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C. The World Book encyclopedia from 2002 lists 1529 °C. 89 Ac actinium (Ac-227 ?)
The melting points of the alkanes follow a similar trend to boiling points for the same reason as outlined above. That is, (all other things being equal) the larger the molecule the higher the melting point. There is one significant difference between boiling points and melting points. Solids have a more rigid and fixed structure than liquids.
Increase in the melting point, boiling point, solubility, and viscosity of many compounds can be explained by the concept of hydrogen bonding. Negative azeotropy of mixtures of HF and water. The fact that ice is less dense than liquid water is due to a crystal structure stabilized by hydrogen bonds.
In aqueous solutions, hydrogen peroxide forms a eutectic mixture, exhibiting freezing-point depression down as low as -56 °C; pure water has a freezing point of 0 °C and pure hydrogen peroxide of -0.43 °C. The boiling point of the same mixtures is also depressed in relation with the mean of both boiling points (125.1 °C). It occurs at 114 ...
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid [ 1][ 2] and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum, i.e., under a lower pressure, has a lower ...