Question

If the pOH of an aqueous NaOH solution is 11.55, what is the [H₃O⁺] for this solution?

Answer 1

Solution:

NaOH is a strong base, which means that it is 100% ionized in solution:

NaOH → Na⁺(aq) + OH⁻(aq)

(pH must be greater than 7).

Therefore, most likely pH is 11.55, not pOH!!!

Assuming pH = 11.55, convert between pH and [H₃O⁺] using the following equation:

pH = − log[H₃O⁺]

[H₃O⁺] = 10^−pH

[H₃O⁺] = 10^−11.55 = 2.82×10⁻¹²

[H₃O⁺] = 2.82×10⁻¹² M

Answer: [H₃O⁺] = 2.82×10⁻¹² M