pH is a unit of measure which describes
the degree of acidity or alkalinity of a
solution. It is measured on a scale of 0
to 14. The term pH is derived from “p,”
the mathematical symbol for negative
logarithm, and “H,” the chemical symbol
for Hydrogen. The formal definition
of pH is: the negative logarithm of
Hydrogen ion activity.
pH = -log[H+] pH provides needed quantitative
information by expressing the degree of
activity of an acid or base in terms of its
hydrogen ion activity.
The pH value of a substance is directly
related to the ratio of hydrogen ion [H+] and hydroxyl ion [OH-] concentrations.
If the H+ concentration is greater than
the OH-, the material is acidic; i.e.,
the pH value is less than 7. If the OHconcentration
is greater than its H+, the
material is basic, with a pH value greater
than 7. If equal numbers of H+ and OHions
are present, the material is neutral,
with a pH of 7.