XV.—The volumetric estimation of mixtures of acids and of bases, and of polybasic acids or bases

Potentiometric Titration in Nonaqueous Solutions

“…Whether or not the second maximum occurs depends upon the relative strengths of the acids, their relative concentrations, and in a special way upon the solvent (6). That conditions are more favorable for the separation of the end points of two acids of different strengths in the solvent n-butyl alcohol than in water is shown by Figure 4.…”

“…HX + j -NaX + HA + ROH Thus the weak acid HA accumulates until the neutralization of the stronger acid HX is completed, and is then itself re-neutralized, causing the appearance of a second maximum on the titration curve. Whether or not the second maximum occurs depends upon the relative strengths of the acids, their relative concentrations, and in a special way upon the solvent (6). That conditions are more favorable for the separation of the end points of two acids of different strengths in the solvent n-butyl alcohol than in water is shown by The above equation clearly shows that an alkali solution, contaminated by a weak acid salt, will be weaker in neutralizing power when titrating a weak acid than when titrating a strong one.…”

“…The collection of the data in this paper was facilitated by the use of the thermionic titrometer, by which the slope of the titration curve is read directly. This instrument also made possible the elimination of neutral salts such as lithium chloride, which have heretofore been used to reduce the resistance of butyl alcohol solutions (4,6).…”

Warder's method for the titration of carbonates

“…The latter precision is a function of the amount of titratable base present, as shown in Equation 2. The absolute precision of the adjustment of the phenolphthalein end point depends altogether on the amount of bicarbonate present at this stage of the titration and is the same as obtained in the titration of an equivalent quantity of carbon dioxide with the use of standard alkali (13,38). It has been demonstrated (IS) that the relative precision, µ /Mi, does not depend on the absolute amount of carbon dioxide present,, if proper judgment is used in the selection of buret and concentration of the standard solution; the relative average deviation of a single adjustment of the phenolphthalein end point has been calculated from the titrations discussed above, and the values *1.2 °/oo (10 titrations) and *1.6%o (5 titrations) were found.…”

Critical Solution Temperatures and Aniline Points of Some Butane Hydrocarbons

“…Chavanne and Simon (2) introduced the use of the critical solution temperature, the maximum miscibility temperature of hydrocarbon-aniline mixtures for the study and analysis of hydrocarbons or hydrocarbon mixtures. A modification was advanced by Tizard and Marshall (13) termed the aniline point, which is the miscibility temperature of equal volumes of hydrocarbon and aniline. Evans (5) pointed out that the differences between the critical solution temperatures and aniline points are usually small and that the two terms have been used indiscriminately.…”