The reaction between potassium bromide (KBr) and calcium sulfide (CaS) is a double displacement reaction where the cations and anions switch partners.

Here's the balanced chemical equation:

2 KBr (aq) + CaS (aq) → CaBr₂ (aq) + K₂S (aq)

Here's a breakdown:

* Reactants:

* Potassium bromide (KBr) is a soluble ionic compound.

* Calcium sulfide (CaS) is also a soluble ionic compound.

* Products:

* Calcium bromide (CaBr₂) is a soluble ionic compound.

* Potassium sulfide (K₂S) is also a soluble ionic compound.

Important Note: This reaction is considered to be a metathesis reaction, but it doesn't actually proceed to a significant extent because all the products are also soluble in water. Essentially, the ions are simply swapped around in solution, and no precipitate forms.