Chain Length Determination of Polyphosphates

Open Access
Publisher Website
Google Scholar
Abstract
The interpretation of titration data from various phosphates is discussed in relation to calculation of chain length of polyphosphates. The weak acid function (fw) is measured by the distance between the two points of inflection in the S-shaped titration curve of the phosphate solution. The strong acid function (fs) is measured similarly after the solution has been hydrolyzed. Sodium tetraphosphate had two weak acid functions (2 fw) per chain (n = 2 fs/fw) while sodium hexametaphosphate had only one weak acid function (fw), then n = fs/fw. Chain length of polyphosphates with ring structures cannot be measured by this procedure. Freezing point data supported the view that hexametaphosphate contains only one weak acid function.