Definition of pH

pH: A measure of the acidity or alkalinity of a fluid. The pH of any fluid is the measure of its hydrogen ion (H+) concentration relative to that of a given standard solution. The pH may range from 0 to 14, where 0 is most acid, 14 most basic, and 7 is neutral.

Mathematically, the pH is the logarithm (to the base 10) of the reciprocal of the hydrogen ion concentration, [H+]. The pH is approximately equal to the negative logarithm of the H+ ion concentration expressed in molarity.

See also: Blood pH; Urine pH.


Last Editorial Review: 8/28/2013

Search MedTerms:


Back to MedTerms online medical dictionary A-Z List
Pill Identifier Tool

Need help identifying pills and medications?
Use the pill finder tool on RxList.


STAY INFORMED

Get the Latest health and medical information delivered direct to your inbox!