Frequently Asked Questions
Why does pH + pOH equal 14?
At 25 degrees C, the ion product of water Kw = [H+][OH-] = 10^-14. Taking -log of both sides gives pH + pOH = 14.
Can pH be negative or above 14?
Yes. Concentrated strong acids can have pH below 0, and concentrated strong bases can exceed 14. The 0-14 range applies to dilute aqueous solutions.