Question

What are the properties of Dihydrogen?

Answer 1

1. Dihydrogen (${\mathbf{H}}_{\mathbf{2}}$) is a colourless, odourless and tasteless gas.
2. It is a neutral molecule neither basic nor acidic.
3. Dihydrogen gas liquifies at $-250°C$ temperature.
4. It is water-insoluble.
5. It has a very high dissociation energy that is $∆H=435.9KJ/mol$. Due to this it is less reactive.
6. On reaction with metals it gives corresponding metal hydride.
7. Example-Sodium (Na) reacts with Hydrogen(${\mathbf{H}}_{\mathbf{2}}$) to give Sodium hydride(NaH).
   $2\mathrm{Na}\left(\mathrm{s}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)\to 2\mathrm{NaH}\left(\mathrm{s}\right)$
8. On reaction with non-metals, it gives respective products.
9. Example- Nitrogen gas (${\mathbf{N}}_{\mathbf{2}}$) reacts with Hydrogen (${\mathbf{H}}_{\mathbf{2}}$) to give Ammonia(${\mathbf{NH}}_{\mathbf{3}}$).
   ${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\to 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$
10. On reaction with unsaturated alkenes it gives saturated alkanes.
11. Example-Ethene reacts with Hydrogen in presence of catalyst gives Ethane.
    ${\mathrm{CH}}_2={\mathrm{CH}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)\stackrel{\mathrm{Ni},473\mathrm{K}}{\to }{\mathrm{CH}}_3-{\mathrm{CH}}_3\left(\mathrm{g}\right)$