Viscometric titrations : A new technique applied to acidimetry and alkalimetry

Abstract

By using a recently designed fully automatic viscometer aliquot portions of one liquid (0.050 ml) can be added in succession from an automatic burette to a second liquid contained in a suspended level viscometer : after mixing, flow-times are measured with a precision of 1 part in l0 6 and the results printed out. When, e. g. an alkali (or acid) is added from the burette to an acid (or alkali) contained in the viscometer the plot of flow-times against the number of aliquots added constitutes a “viscosity titration curve”. This novel technique is illustrated by curves for the titration by hydrochloric acid of sodium hydroxide, ammonia, pyridine, a mixture of ammonia and pyridine, and ethylenediamine. The titration of mono-, di-, tri- and tetra-basic acids of various strengths by sodium hydroxide is illustrated by graphs for hydrochloric and acetic acids, phenol, sulphuric and oxalic acids, citric and phosphoric acids, and EDTA and DCTA. Salicylic acid titrated as a dibasic acid in methanol. The graphs form a series of straight lines intersecting at the stoicheiometric end-points and it is noteworthy that the titration of ammonia is not adversely affected by a high concentration (l M) of neutral salts.