Hydroxide Ion Concentration from pOH

What is this formula?

This formula calculates the hydroxide ion concentration from a known pOH value. It is the inverse of the pOH definition and is commonly used in analytical chemistry, water treatment, and chemical engineering.

When to use it

Use this formula when pOH measurements are available and the hydroxide ion concentration is needed for equilibrium calculations, process control, or solution preparation.

Example

A solution has:

pOH = 3.20

Formula:

[OH⁻] = 10^(-pOH)

Substitution:

[OH⁻] = 10^(-3.20)

Result:

[OH⁻] = 6.31×10⁻⁴ mol/L

The hydroxide ion concentration is 6.31×10⁻⁴ mol/L.

Applications

- Acid-base equilibrium calculations

- Water treatment systems

- Environmental monitoring

- Industrial chemistry

- Laboratory analysis

- Chemical process control

Note

Because pOH is logarithmic, small changes in pOH correspond to large changes in hydroxide ion concentration. A decrease of one pOH unit corresponds to a tenfold increase in [OH⁻].