The pH scale indicates the degree of acidity or alkalinity of a solution. Definition of pH is the logarithm of the reciprocal of the hydrogen-ion \((H^+)\) concentration. Scale range is usually 0 to 14 where the midpoint is 7.0. When the pH is 7.0, the fluid is said to be neutral. Higher values denote alkalinity; lower values denote acidity. When pH is 0, the solution is the most acidic. When the pH is 14, the solution is most basic.