Calcium hydroxide as a highly alkaline pH standard

Abstract

The National Bureau of Standards conventional activity scale of pH is defin ed by a series of standard buffer solution s prepared from certified materials issued as N BS Stan dard Samples. The five standards thus far established cover the pH range 1.68 to 9.18 at 25 . In order to increa e t he accuracy of m easurements at high pH, a highly alkaline standard is needed.