Explain about Hydrogen sponge.

Explanation

Hydrogen sponge (or) Metal hydride e.g., palladium-hydrogen system is a binary hydride (PdH).
(ii) Upon heating, H atoms diffuse through the metal to the surface and recombine to form molecular hydrogen. Since no other gas behaves this way with palladium, this process has been used to separate hydrogen gas from other gases: `2Pd_((s))+H_(2(g))leftrightarrow2PdH_((s))`
(iii) The hydrogen molecule readily adsorb on Interface the palladium surface, where it dissociates Metal into atomic hydrogen. The dissociated atoms dissolve into the interstices or voids (octahedral or tetrahedral) of the crystal lattice.
(iv) Technically, the formation of metal hydride is by chemical reaction but it behaves like a physical storage method, ie, it is absorbed and released like a water sponge. Such a reversible uptake of hydrogen in metals and alloys is also attractive for hydrogen storage and for rechargeable metal hydride battery applications.