Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)
Explanation:
Magnesium is a relatively reactive metal, meaning it readily loses electrons to other atoms or molecules. Hydrochloric acid is a strong acid that dissociates in water to form hydrogen ions (H+) and chloride ions (Cl-).
When magnesium comes into contact with hydrochloric acid, the magnesium atoms lose two electrons each, becoming positively charged magnesium ions (Mg2+). These magnesium ions are then attracted to the negatively charged chloride ions, forming an ionic bond and creating magnesium chloride (MgCl2).
At the same time, the hydrogen ions from the hydrochloric acid react with the electrons lost by the magnesium atoms to form hydrogen gas (H2). The hydrogen gas is released as a colourless, odourless gas that bubbles out of the solution.
The overall reaction is exothermic, meaning that heat is released as the products are formed. This can be observed as a slight increase in the temperature of the reaction mixture.
This reaction is a classic example of a single-replacement reaction, where one element (magnesium) replaces another element (hydrogen) in a compound (hydrochloric acid).
