Lithium metal is a highly reactive alkali metal that reacts violently with water to produce hydrogen gas and lithium hydroxide. However, in the presence of hydrochloric acid, lithium undergoes a different reaction pathway, resulting in the formation of lithium chloride and hydrogen gas. The reaction can be represented by the following equation:

2Li(s) + 2HCl(aq) → 2LiCl(aq) + H2(g)

Here's a detailed explanation of the reaction:

1. Initial Dissolution: When lithium metal is added to hydrochloric acid, it undergoes a rapid dissolution process. The lithium atoms react with water molecules present in the acid to form hydrated lithium ions (Li+) and hydrogen gas (H2). This reaction can be represented as:

Li(s) + H2O(l) → Li+(aq) + OH-(aq) + 1/2 H2(g)

2. Reaction with Hydrochloric Acid: The hydrated lithium ions (Li+) produced in the first step further react with hydrochloric acid (HCl) molecules. The hydrogen ions (H+) from HCl displace the lithium ions, forming lithium chloride (LiCl). This reaction can be represented as:

Li+(aq) + Cl-(aq) → LiCl(aq)

3. Evolution of Hydrogen Gas: The reaction between lithium and hydrochloric acid produces hydrogen gas (H2) as a byproduct. Hydrogen gas is a flammable gas and can be observed as bubbles rising to the surface of the solution.

Overall, the reaction between lithium and hydrochloric acid can be summarized as:

2Li(s) + 2HCl(aq) → 2LiCl(aq) + H2(g)

It's important to note that this reaction should be carried out with caution under controlled conditions as lithium is a highly reactive metal and the reaction can be vigorous, releasing flammable hydrogen gas.