How do hydroxyl ions and hydronium ions affect ph?

Hydroxyl ions are OH⁻ while hydronium ions are H₃O⁺ which is essentially H⁺ ions. The formula for pH is: pH = -log[H⁺]. So, the greater the concentration of H⁺ is, the lower the pH which indicates acidity. On the other hand, the greater the concentration of OH⁻, the greater the pH which indicates basicity. This is also a consequence of the equation: pH + pOH = 14.

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