Final answer:
KOH (Potassium Hydroxide) is a classic example of an Arrhenius base, as it directly increases the concentration of hydroxide ions in aqueous solution when dissolved in water. Although Na2CO3, Na3PO4, and K2S can also produce hydroxide ions, KOH is the most straightforward and classic choice.
Step-by-step explanation:
An Arrhenius base is defined as a substance that increases the hydroxide ion (OH-) concentration in aqueous solution. Let's look at the given options:
- Na2CO3 (Sodium Carbonate): When dissolved in water, it can hydrolyze to form sodium hydroxide (NaOH) and carbonic acid (H2CO3), thus it can behave as an Arrhenius base due to the production of OH- ions.
- Na3PO4 (Sodium Phosphate): It also undergoes hydrolysis in water, producing OH- ions due to the weak acidity of the HPO42- ion.
- K2S (Potassium Sulfide): Similar to the above salts, it can also hydrolyze to form KOH and H2S, giving rise to OH- ions.
- KOH (Potassium Hydroxide): This is a classic example of an Arrhenius base as it directly provides OH- ions when dissolved in water.
Among the options provided, the one that would classically behave as an Arrhenius base by definition is KOH.