pOH Calculator
pOH, pH and both ion concentrations, with the 14 explained.
Work out pOH. pOH, pH and both ion concentrations, with the 14 explained. Names the convention that makes the answer wrong.
pOH
11
pH 3 · acidic
pOH is the hydroxide mirror of pH, and at 25 °C the two sum to 14 because that is the negative logarithm of water's ion product. That 14 is not a constant of nature: Kw rises with temperature, so at 50 °C the sum is nearer 13.3 and neutral water sits at pH 6.6 while remaining exactly neutral. Neutrality means equal ion concentrations, not pH 7.
How the pOH Calculator works
pOH is the hydroxide mirror of pH, and at 25 °C the two sum to 14 because that is the negative logarithm of water's ion product. That 14 is not a constant of nature — it shifts with temperature.
Also known as: ph to poh converter · hydroxide ion concentration calculator · poh formula · how to calculate poh
Frequently asked questions
How do I convert pH to pOH?
Subtract from 14 at 25 °C. A pH of 3 is a pOH of 11.
Why do pH and pOH sum to 14?
Because water's ion product Kw is 10⁻¹⁴ at 25 °C. Taking negative logarithms of both sides gives pH + pOH = 14.
Does that sum change?
Yes. Kw rises with temperature, so at 50 °C the sum is nearer 13.3 and neutral water sits at pH 6.6 while remaining exactly neutral. Neutrality means equal ion concentrations, not pH 7.
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