pH scale
n : (chemistry) p(otential of) H(ydrogen); 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 acidic and less than 7 is
basic) [syn: pH]