pH – quantitative measure of the acidity or basicity of aqueous or other liquid solutions.
The term, widely used in chemistry, biology, and agronomy, translates the values of the concentration of the hydrogen ion, which ordinarily ranges between about 1 (10–0) and 10−14 gram-equivalents per litre, into numbers between 0 and 14.
The color on ph scale depends on the indicator used.
pH scale of SULFOMI