What is nascent hydrogen?

The meaning of nascent is newly born. In context of chemical reaction, nascent hydrogen or element means such elements which are produced in situ and are highly reactive elements compared to their ordinary forms. That is nascent hydrogen is more reactive than molecular hydrogen.

When Zinc is passed through dil H₂SO_4, nascent hydrogen is produced as:

Zn + dil. H₂SO_4    →  ZnSO₄ + 2[H]

This nascent hydrogen is considered to be atomic hydrogen unlike ordinary molecular hydrogen (H₂). However it is also suggested that nascent hydrogen is a molecular hydrogen but in higher energy state than that of molecular one.

Reactivity of nascent hydrogen:

Nascent hydrogen is very reactive due to which it reacts with chemicals which don’t react with molecular hydrogen in normal condition. There are examples of strong reducing properties of nascent hydrogen which is not shown by ordinary hydrogen, but first let’s discuss why nascent hydrogen is more reactive than molecular hydrogen.

There are two major reasons for higher reactivity of nascent hydrogen.

• The production of nascent hydrogen is associated with the release of high energy. This released energy activates the nascent hydrogen and makes it more energy rich than that of ordinary occurring molecular hydrogen. Because more energy means more reactivity, nascent hydrogen is more reactive than molecular hydrogen.
• The second reason for higher reactivity of nascent hydrogen is related with the high internal pressure. In the time of formation nascent hydrogen is in the form of minute bubbles with high internal pressure which makes it more reactive.

 The reactivity of nascent hydrogen can be illustrated by following reactions:

•         Reaction with Potassium

                     Zn + dil. H₂SO_4   →   ZnSO₄ + 2[H]

                  2KMnO₄ + 3 H₂SO₄ +10 [H]  _→    K₂SO₄ + 2MnSO₄ + 8H₂0.

The nascent hydrogen reduces the permanganate solution, which is pink into colorless manganate salt. Ordinanry hydrogen don’t react with KMnO_{4 .}