The reaction between hydrochloric acid (HCl) and zinc (Zn) is an example of a single-displacement reaction. In a single-displacement reaction, one element replaces another element in a compound. In this case, the zinc replaces the hydrogen in hydrochloric acid to form zinc chloride (ZnCl2) and hydrogen gas (H2).

Zinc chloride is formed as a result of the reaction between zinc and hydrochloric acid. Hydrogen gas is released because it is a product of the reaction. The reaction can be represented by the following equation:

Zn + 2HCl --> ZnCl2 + H2

In this equation, Zn represents zinc, HCl represents hydrochloric acid, ZnCl2 represents zinc chloride, and H2 represents hydrogen gas.