When hydrogen chloride gas (HCl) is dissolved in water, it undergoes a chemical reaction with water molecules to form hydronium ions (H3O+) and chloride ions (Cl-). This reaction is represented by the following equation:

HCl + H2O → H3O+ + Cl-

As a result of this reaction, the hydrogen chloride gas is no longer present in the solution as HCl molecules. Instead, the solution contains hydronium ions and chloride ions. However, for convenience and simplicity, we still refer to the solution as hydrochloric acid (HCl) even though the actual chemical species present are H3O+ and Cl-.

It's important to note that the formula HClO3 does not represent hydrochloric acid. HClO3 is the chemical formula for chloric acid, which is a different compound entirely.