Question

Metals like platinum and palladium can adsorb large volumes of hydrogen under special conditions. Such absorbed hydrogen by the metal is known as
A. Absorbed hydrogen
B. Occluded hydrogen
C. Reactive hydrogen
D. Atomic hydrogen

Answer 1

Hint: A large volume of hydrogen can be adsorbed by metals such as palladium (Pd) and platinum (Pt). Generally, palladium adsorbs a thousand times its volume of hydrogen. This process is very useful to purify hydrogen. This adsorbed hydrogen is more reactive than ordinary hydrogen.

Complete Step by Step Answer:
Adsorption is a physical or chemical phenomenon in which a substance such as solids, liquids, or dissolved solids adhere or adhere to the surface of another metal surface that can be solid or liquid. Adsorption is a surface phenomenon.

The adsorption of hydrogen on transition metals like palladium and platinum is a very important process occurring in both catalytic and surface chemistry. Though the reactions which take place on the catalytic surface are very complicated, the behaviour of hydrogen can have a large impact on the overall performance of the catalytic surface. The hydrogen that is adsorbed on the surface of metals like Pt and Pd under certain conditions, is called Occluded hydrogen.

It is an energetically favourable process even at room temperature and pressure. Hydrogen molecules are dissociated at the surface of a Pd and Pt lattice and diffused into the lattice as individual hydrogen atoms. The adsorbed hydrogen is more active than ordinary hydrogen. This occultation process is extensively used to purify hydrogen as only pure hydrogen is adsorbed on the surface of the metal.
Thus, option (B) is correct.

Note: The hydrogen molecule (${{H}_{2}}$) has two electrons and has lesser intermolecular forces of attraction. Hydrogen molecules have weaker van der waal forces. As we know, higher the value of critical temperature, the more easily a gas will be liquefied. But hydrogen has a lower value of critical temperature and it cannot be easily adsorbed on activated charcoal.