The answer is: emitted gas is carbon dioxide (CO₂).
Neutralization is is reaction in which an acid (in this example vinegar or acetic acid CH₃COOH) and a base (in this example soda)
Balanced chemical reaction of vinegar and antacid:
CH₃COOH(aq) + NaHCO₃(aq) → CH₃COONa(aq) + H₂O(l) + CO₂(g).
Sodium acetate (CH₃COONa) is a salt.
Sodium bicarbonate (NaHCO₃) is an antacid. Sodium bicarbonate is the active ingredient in baking soda.
