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pH Definition

Chemistry Glossary Definition of pH


pH is a measure of hydrogen ion concentration.

pH is a measure of hydrogen ion concentration in a water-based solution.

Todd Helmenstine
pH Definition: pH is a measure of hydrogen ion concentration; a measure of the acidity or alkalinity of a solution. Aqueous solutions at 25°C with a pH less than seven are acidic, while those with a pH greater than seven are basic or alkaline. A pH level of is 7.0 at 25°C is defined as 'neutral' because the concentration of H3O+ equals the concentration of OH in pure water.


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