Why Ammonium Hydride (NH4 H-) Does Not Exist

Ammonium hydride, which would be represented as NH_4^{ }cdot H^{-}, does not exist due to a combination of factors related to stability, bonding, and the nature of the ions involved. This article delves into the reasons behind this phenomenon, exploring the ionic nature, hydride properties, and the instability of the compound.

Ionic Nature

Ammonium NH_4^{ }, a positively charged ion (cation), and hydride H^{-}, a negatively charged ion (anion), form cation-anion pairs that are capable of forming stable ionic compounds. However, the specific combination of NH_4^{ } and H^{-} is not stable.

Hydride Properties

Hydride ions are known as strong bases and strong reducing agents. When these ions react with other species, they tend to donate their extra electron rather than remain as a stable ion. This tendency makes the formation of stable compounds with hydride less likely.

Instability of the Compound

The combination of NH_4^{ } and H^{-} would likely result in an unstable compound. Instead of forming ammonium hydride, the hydride would react with water or other species, leading to the formation of ammonia NH_3 and hydrogen gas H_2. This reaction is very far to the right, with the products being the more favored species.

Reaction Equation: NH_4 H- → NH_3 H_2

In other words, the reaction is highly unlikely due to the transition state involving unstable intermediates. Anhrea, however, only applies to the spontaneity of the reaction. Technical means can, in theory, allow for the existence of such a compound in a controlled environment.

Absence in Literature

There is no significant evidence or documentation of a stable compound that can be accurately described as ammonium hydride. Instead, ammonium salts like ammonium chloride NH_4Cl exist, where NH_4^{ } is paired with different anions.

Conclusion

In summary, the combination of ammonium and hydride does not lead to a stable compound due to the inherent properties and reactivity of the ions involved.

While we have not found evidence of its existence, there is no reason to believe that ammonium hydride cannot exist under specifically designed experimental conditions. It's a hypothetical substance that may exist under controlled experimental settings, similar to the querying of whether GD does not exist, as we lack evidence of its non-existence.