Hydroxide Ion Concentration Calculator

The Hydroxide Ion Concentration Calculator estimates hydroxide ion concentration based on pH, pOH, and temperature. This tool helps chemistry students and professionals determine solution basicity quickly and accurately. Whether you are analyzing chemical equilibrium, preparing buffers, or treating wastewater, this calculator provides precise results for better lab work.

Choose whether you're providing pH or pOH value
Temperature affects the water ion product constant (Kw)

How Hydroxide Ion Concentration Is Calculated

Hydroxide ion concentration measures the amount of hydroxide ions present in a specific volume of liquid. To find this value, we use the inverse log function of the pOH value.

[OH⁻] = 10^(-pOH)

Where:

  • [OH⁻] is the hydroxide ion concentration in moles per liter (M)
  • pOH is the measure of hydroxide ion activity

The calculation first converts your pH input to pOH using the water ion product constant. Then, it calculates the antilog to find the molarity. This method is essential for translating the abstract pH scale into a measurable concentration used in chemical reactions.

What Your Hydroxide Ion Concentration Means

This number tells you exactly how basic a solution is on a molecular level. It moves beyond a simple pH number to show the actual chemical strength of the mixture.

  • Neutral Solution: If your result is 1.0 × 10⁻⁷ mol/L at 25°C, the solution is neutral. This means the acidity and basicity are perfectly balanced, which is typical for pure water.
  • Basic Solution: Values greater than 1.0 × 10⁻⁷ mol/L indicate a basic solution. For example, blood plasma has a concentration around 2.5 × 10⁻⁷ mol/L, which is slightly basic.
  • Strongly Basic Solution: If the result exceeds 1.0 × 10⁻³ mol/L, the substance is strongly basic. Common household cleaners often fall into this range and can be corrosive.

Important: Always double-check your temperature setting. Higher temperatures increase the water ion product constant, which changes the neutral point and affects your final concentration value.

This calculator is intended for educational and informational purposes only. It assumes ideal behavior and may not account for ionic strength in highly concentrated solutions. For critical laboratory work or industrial applications, consult standard chemical references or a qualified professional.

For the best accuracy, always calibrate your pH meter before measuring inputs for this calculation.