Answer:
The Arrhenius theory defines an acid as a substance that increases the concentration of hydrogen ions (H+) in an aqueous solution and a base as a substance that increases the concentration of hydroxide ions (OH-) in an aqueous solution.
To determine if Ba(OH)2 is an acid or a base, we can write an Arrhenius reaction:
If Ba(OH)2 is a base, it will dissociate in water to form Ba2+ ions and OH- ions, according to the equation:
Ba(OH)2(s) → Ba2+(aq) + 2OH-(aq)
If Ba(OH)2 is an acid, it will react with water to form Ba2+ and H3O+ ions, according to the equation:
Ba(OH)2(s) + H2O(l) -> Ba2+(aq) + 2H2O(l)
As we can see, in the first reaction Ba(OH)2 is a base, it will dissociate in water to form Ba2+ ions and OH- ions. Ba(OH)2 is a strong base and it can neutralize an acid, forming water and a salt.