When potassium is added to hydrochloric acid, a reaction takes place which produces potassium chloride and hydrogen gas. The chemical equation for this reaction is:

*2K(s) + 2HCl(aq) → 2KCl(aq) + H2(g)*

Potassium is a highly reactive metal, which means that it readily undergoes chemical reactions. Hydrochloric acid is a strong acid, meaning that it completely dissociates in water to form hydrogen ions (H+) and chloride ions (Cl-). When the potassium is added to the hydrochloric acid, the potassium atoms donate their outermost electrons to the hydrogen ions, reducing them to hydrogen gas (H2). The chloride ions then combine with the potassium ions to form potassium chloride (KCl), which is a soluble salt.