The reaction between ammonia and hydrochloric acid is an acid-base reaction, also known as a neutralization reaction. In this type of reaction, an acid and a base react to form a salt and water.

The chemical equation for the reaction between ammonia and hydrochloric acid is:

$$NH_3(aq) + HCl(aq) → NH_4Cl(aq)$$

In this reaction, ammonia acts as the base and hydrochloric acid acts as the acid. The products of the reaction are ammonium chloride, which is a salt, and water.

Acid-base reactions are typically characterized by the transfer of protons (H+) from the acid to the base. In this case, the proton from the hydrochloric acid is transferred to the ammonia, resulting in the formation of ammonium ions (NH4+) and chloride ions (Cl-). The ammonium and chloride ions then combine to form ammonium chloride, which is a white, crystalline solid that is soluble in water.