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pH & pOH Calculator

Calculate pH, pOH, and ion concentrations ([H+] and [OH-]) with precision for laboratory analysis.

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pH / pOH Calculator

Instantly convert between pH, pOH, Hydrogen ion concentration [H⁺], and Hydroxide ion concentration [OH⁻].

The pH scale

The pH scale measures how acidic or basic a substance is. It ranges from 0 to 14. A pH of 7 is neutral (like pure water). A pH less than 7 is acidic, and a pH greater than 7 is basic.

Key Formulas

pH = -log₁₀[H⁺]

pOH = -log₁₀[OH⁻]

pH + pOH = 14 (at 25°C)

This science solver is useful for chemistry students, laboratory technicians, and environmental scientists monitoring water quality and solution acidity.

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The Fundamentals of pH and pOH

In the science category, pH is a measure of the acidity or basicity of an aqueous solution. Working on the principle of a negative logarithmic scale, it tracks the concentration of hydrogen ions (H+). This chemistry solver allows you to toggle between pH, pOH, [H+], and [OH-], providing a complete picture of the solution's acid-base equilibrium.

The scale typically runs from 0 to 14, where 7 is neutral (at 25°C). Values below 7 are acidic, while values above 7 are alkaline (basic). Understanding these values is crucial for everything from soil testing in agriculture to maintaining the delicate balance of human blood.

How to Calculate pH and Concentrations

This science solver uses the standard logarithmic relationships:

  • pH to [H+]: [H+] = 10-pH
  • [H+] to pH: pH = -log[H+]
  • pH and pOH relationship: pH + pOH = 14 (at standard temperature).

For accurate background information on these constants, refer to the American Chemical Society (ACS) resources.

Common pH Reference Values

Battery Acid: ~0
Lemon Juice: ~2.0
Black Coffee: ~5.0
Pure Water: 7.0
Baking Soda: ~9.0
Bleach: ~13.0

Chemistry FAQ

Can pH be negative?

Yes. For extremely concentrated solutions of strong acids, the [H+] concentration can be greater than 1 M, resulting in a negative pH value. This tool handles such concentrations with precision.

Does temperature affect pH?

Absolutely. The autodissociation of water is an endothermic process. As temperature increases, Kw increases, and the "neutral" pH value actually drops below 7.0.

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