Question

How do you calculate the molar mass of heavy water?

Answer 1

Step 1: Heavy water configuration:-

Heavy water with the chemical formula, ${\mathrm{D}}_2\mathrm{O}$ is formed when replaced with ${}^1\mathrm{H}$ isotope, which is generally present in most of the water molecules, with deuterium as ${}^2\mathrm{H}$ isotope .

In heavy water, there is a presence of deuterium instead of Hydrogen, and while regular hydrogen has a proton in its nucleus, deuterium has both a proton and a neutron.

Step 2: Calculating the molar mass of heavy water:-

We know that deuterium has a molar mass of $=2.0141{\mathrm{gmol}}^{-1}$

Therefore, the molar mass of heavy water, which contains two deuterium isotopes and one oxygen atom, can be calculated as follows:

$$\begin{gathered} \mathrm{Molarmass}\left({\mathrm{D}}_2\mathrm{O}\right)=2\times 2.0141\mathrm{g}{\mathrm{mol}}^{-1}+15.9994\mathrm{g}{\mathrm{mol}}^{-1} \\ =20.0276\mathrm{g}{\mathrm{mol}}^{-1} \end{gathered}$$
Hence, the molar mass of heavy water can be calculated as given above and found to be :$=20.0276\mathrm{g}{\mathrm{mol}}^{-1}$.