The reaction of hydrogen chloride gas (HCl) with barium hydroxide (Ba(OH)₂) is a neutralization reaction, producing a salt and water. Here's the balanced chemical equation:

2 HCl(g) + Ba(OH)₂(aq) → BaCl₂(aq) + 2 H₂O(l)

Explanation:

* Reactants:

* Hydrogen chloride (HCl): A colorless gas with a pungent odor, highly soluble in water.

* Barium hydroxide (Ba(OH)₂): A white, crystalline solid that is also soluble in water.

* Products:

* Barium chloride (BaCl₂): A white, crystalline solid, soluble in water.

* Water (H₂O): A liquid formed by the reaction of H+ and OH- ions.

Important Notes:

* This reaction is exothermic, meaning it releases heat.

* The reaction is balanced, meaning there are equal numbers of atoms of each element on both sides of the equation.

* The states of matter are indicated in parentheses: (g) for gas, (aq) for aqueous (dissolved in water), and (l) for liquid.