In chemistry, pH is a measure of how acidic something is. The lower the number on the pH scale, the more acid a substance contains.

The pH scale goes from 0 to 14, with 0 being the most acidic. The higher, low-acid numbers on the pH scale are basic — they feel slippery and have an astringent taste. Substances at around 7, the middle of the pH scale, are neutral, like water. Lemon juice has a pH of 2.2, since it's acidic. pH comes from the German word Potenz, "potency or power," and H, the chemical symbol for hydrogen.

Definitions of pH

n (from potential of Hydrogen) the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter; provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is more basic and less than 7 is more acidic);

pH scale
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pH values below 7
pH values above 7
pH value of 7
excessive acidity
Type of:
hydrogen ion concentration
the number of moles of hydrogen ions per cubic decimeter

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