When is solution acidic or basic?

When is solution acidic or basic?

An aqueous solution is acidic when its hydronium ions (H₃O⁺) are greater than its hydroxide ions (OH^–).

An aqueous solution is basic when its hydroxide ions (OH^–) are greater than its hydronium ions (H₃O⁺).

Thus, we can say that

• acidic solutions have a greater concentration of hydronium ions than hydroxide ions. We can express this concentration as: [H₃O⁺] > [OH^–]
• Basic solutions have a greater concentration of hydroxide ions than hydronium ions.

We can express this concentration as: [OH^–] > [H₃O⁺]

• Neutral solutions have the same concentration of hydroxide and hydronium ions.

We can express this concentration as: [OH^–] = [H₃O⁺]

The square brackets represent concentration: [concentration]. And here concentration means the number of hydronium(H₃O⁺) or hydroxide (OH^–) ions in a liter of solution.