Question

What is the molar mass of deuterium gas, $^{2}{{H}_{2}}$ ?

Answer 1

The mass of a sample of a chemical compound divided by the amount of material in that sample, measured in moles, is the molar mass of that compound in chemistry. In grams, it is the mass of 1 mole of the material, or $6.022\times {{10}^{23}}$ particles. The molar mass of a material is a bulk characteristic, not a molecular property. The molar mass is a weighted average of several different occurrences of the chemical, which might vary in mass due to isotopes.

Complete answer:
Deuterium (D, or $^{2}H$ ), commonly known as heavy hydrogen, is a hydrogen isotope with a nucleus that consists of one proton and one neutron and has twice the mass of regular hydrogen's nucleus (one proton). The atomic weight of deuterium is 2.014. It's a stable atomic species that makes up approximately 0.0156 percent of natural hydrogen compounds.
To make things easier, we know that one mole of hydrogen gas, $^{2}H$ , weighs 2.0 gram. A deuterium ATOM, i.e. 2H, possesses both a proton and a neutron in its nucleus (necessarily since this is how we define the hydrogen atom, i.e. Z = 1, where Z is the atomic number). As a result, the mass of the deuterium nucleus is twice that of the hydrogen nucleus. In the nuclear core, the neutron and proton interact attractively.
Furthermore, its large mass difference from protium ( $^{1}H$ ) (deuterium has a mass of 2.014102 u, compared to the mean hydrogen atomic weight of 1.007947 u and protium's mass of 1.007825 u) confers non-negligible chemical differences with protium-containing compounds, whereas isotope weight ratios within other chemical elements are largely insignificant in this regard).

Note:
The availability of deuterated samples benefits neutron scattering methods in particular: The H and D cross sections are extremely distinct and have opposite signs, allowing for contrast change in these studies. Furthermore, conventional hydrogen has a high incoherent neutron cross section, which is nil for D, which is a nuisance problem. By substituting deuterium atoms for hydrogen atoms, scattering noise is reduced.