The process 1/2 `H_(2)(g) + e^(-) to H^(-)(g)` is endothermic `(DeltaH=+151 KJ "mol"^(-1))` , yet salt like hydrides are known. How do you account for this ?

The process 1/2 `H_(2)(g) + e^(-) to H^(-)(g)` is endothermic `(DeltaH

1.	The process 1/2 `H_(2)(g) + e^(-) to H^(-)(g)` is endothermic `(DeltaH=+151 KJ "mol"^(-1))` , yet salt like hydrides are known. How do you account for this ?
Answer» It is true that formation of hydride `(H^(-))` ion is an endothermic process, yet alkali and alkaline earth metals form salt like hydrides. This is due to the reason that high lattice energy released (energy released during the formation of solid metal hydrides from their correspoinding gaesous ions, `M^(+) (g) and H^(-)(g))` more than compensates the energy needed for the formation of `H^(-)` ions from `H_(2)` gas.

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The process 1/2 `H_(2)(g) + e^(-) to H^(-)(g)` is endothermic `(DeltaH=+151 KJ "mol"^(-1))` , yet salt like hydrides are known. How do you account for this ?

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