Ammonium sulfide ((NH₄)₂S) and calcium bromide (CaBr₂) react in a double displacement reaction to form ammonium bromide (NH₄Br) and calcium sulfide (CaS).

Here's the balanced chemical equation:

(NH₄)₂S + CaBr₂ → 2NH₄Br + CaS

Let's break down the reaction:

* Double Displacement: The positive and negative ions of the reactants switch partners.

* Ammonium bromide: Ammonium ions (NH₄⁺) from ammonium sulfide combine with bromide ions (Br⁻) from calcium bromide.

* Calcium sulfide: Calcium ions (Ca²⁺) from calcium bromide combine with sulfide ions (S²⁻) from ammonium sulfide.

Important Note: This reaction produces a precipitate (solid) of calcium sulfide.