When you add a reactive metal to an acid, hydrogen ions (H+) are displaced from the acid.

Here's a breakdown:

* Reactive metal: Metals like sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), aluminum (Al), zinc (Zn), and iron (Fe) are considered reactive.

* Acid: Acids contain hydrogen ions (H+) and an anion. For example, hydrochloric acid (HCl) contains H+ and Cl-.

* Reaction: The reactive metal displaces the hydrogen ions from the acid, forming a metal salt and releasing hydrogen gas (H2).

Example:

Zinc (Zn) + Hydrochloric acid (HCl) → Zinc chloride (ZnCl2) + Hydrogen gas (H2)

In this reaction, the zinc metal reacts with the hydrochloric acid, displacing the hydrogen ions. The zinc forms zinc chloride, and the hydrogen ions combine to form hydrogen gas, which is released as bubbles.