What is the reaction between silver bromide and ammonia?

Answer 1

2 AgBr (s) + 2 NH4OH (aq) --> Ag2O (s) + H2O (l) +2 NH4Br (aq)

The reaction does not proceed rapidly as in the case of AgCl as AgBr is only slightly soluble in ammonium hydroxide. With more NH4OH, the brown/black Ag2O dissolves forming the soluble salt Silver Di-amine hydroxide:

Ag2O (s) + 4 NH4OH --> 2 [Ag(NH3)2]OH + 3 H2O

I suspect that this reaction is reversible and the loss of NH3 would push the reaction to the left, which may occur naturally with time. This is a major problem as the precipitated Ag2O can further react with NH4OH to form Silver nitride, Ag3N:

2 NH4OH (aq) + 3 Ag2O (s) --> 2 Ag3N (s) + 5 H2O

Silver nitride can be a highly sensitive and powerful contact explosive, even when in solution. This has been ascribed to be the cause of many injuries, and as such, solutions of [Ag(NH3)2]OH should not be stored for safety concerns.