In the reaction of HBr(aq) and NH3(aq), the spectator ions are:

Answer

To identify the spectator ions, we must write the balanced chemical equation, the total ionic equation, and then see which ions appear unchanged on both sides. 1) Molecular equation: HBr(aq) + NH3(aq) -> NH4Br(aq). 2) Total ionic equation: HBr is a strong acid, so it dissociates completely into H+(aq) and Br-(aq). NH3 is a weak base, so it remains primarily as NH3(aq). The product NH4Br is a soluble salt, so it exists as NH4+(aq) and Br-(aq). This gives: H+(aq) + Br-(aq) + NH3(aq) -> NH4+(aq) + Br-(aq). 3) Net ionic equation: By crossing out the ions that appear on both sides in identical form, we see that Br-(aq) is the only ion that does not participate in the reaction. The H+ reacts with NH3 to form NH4+. Therefore, the only spectator ion is Br-(aq). The correct choice is 'Just Br-(aq)'.