Question

The adsorption of hydrogen on platinum black is called:
A.Hydrogenation
B.Reduction
C.Occlusion
D.Hydration

Answer 1

Adsorption is a surface phenomenon. If the adsorption occurs on metals it is called occlusion.If the surface area of the adsorbent increases, the rate of adsorption will also increase.

Complete step by step answer:
First, we have to know what these processes are.
Hydrogenation is an exothermic reaction. It is a chemical reaction between hydrogen and other substances. Hydrogenation occurs only in presence of a catalyst.
A decrease in the oxidation number of an element occurs in the reaction it is called reduction and the reagent which can lower the oxidation state is called reductant.
Absorption and adsorption are different. Absorption is a bulk phenomenon. But adsorption is a surface phenomenon. Adsorption is the accumulation of a species at the surface of a bulk of a solid or liquid. The material which is getting adsorbed is known as adsorbate and the surface on which adsorption takes place is known as adsorbent.
Occlusion is a type of adsorption in which adsorption of gases on metals happens. Here hydrogen is adsorbed on platinum. Hydrogen is a gas and platinum is a metal So this is an example of occlusion, and this hydrogen is known as occluded hydrogen. This hydrogen will be more active than the ordinary hydrogen. This is used as a catalyst in various reactions. Occlusion of hydrogen by platinum, palladium, iron etc are well known.
Hence the correct answer is C.

Note: There are mainly two types of adsorption of gases on solids. There is physical adsorption or physisorption and chemical adsorption or chemisorption. In physisorption weak vander waals forces are present and this require only small activation energy. While the chemisorption requires high activation energy and the chemical bond may be covalent or ionic in nature.