Adsorption Indicators

Püngor, E.; Schulek, E.

doi:10.1016/b978-0-08-016617-9.50013-8

Cited by 2 publications

(4 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…the surface of the silver halides is positively charged. This is used in the Fajans methods [18][19][20] of indication using adsorption indicators, where, as an example, fluorescein anions are used as they are adsorbed on the positively charged surface of silver halides. The adsorption changes the colour of the silver halide precipitate, which serves as indication of the equivalence point.…”

Section: Distribution Of Ions Between the Solid Salt Phase And The Samentioning

confidence: 99%

The partition of salts (i) between two immiscible solution phases and (ii) between the solid salt phase and its saturated salt solution

2020

View full text Add to dashboard Cite

The partition of salts between two polar immiscible solvents results from the partition of the cations and anions. Because electroneutrality rules in both phases, the partition of cations is affected by that of anions, and vice versa. Thus, the partition of a salt is determined by the chemical potentials of cations and anions in both phases, and it is limited by the boundary condition of electroneutrality. Whereas the partition of neutral molecules does not produce a Galvani potential difference at the interface, the partition of salts does. Here, the equations to calculate this Galvani potential difference are derived for salts of the general composition Cat ðz Cat Þþ m Cat An ðz An ÞÀ m An and for uni-univalent salts Cat þ An À. The activity of a specific ion in a particular phase can thus be purposefully tuned by the choice of a suitable counterion. Finally, the distribution of a salt between its solid phase and its saturated solution is also presented, together with a discussion of the Galvani potential difference across the interface of the two phases.

show abstract

Section: Distribution Of Ions Between the Solid Salt Phase And The Samentioning

confidence: 99%

The partition of salts (i) between two immiscible solution phases and (ii) between the solid salt phase and its saturated salt solution

2020

View full text Add to dashboard Cite

show abstract

“…Among these chemical methods, the volumetric titrations with precipitation with Ag + have been most popular because it is less time consuming than the gravimetry. Several different ways of determining the equivalence point have been reported for the volumetric titrations with silver ion, such as (a) use of various visual indicators [ 11 , 12 ], (b) thermometric titration measuring enthalpy changes [ 13 ], and (c) potentiometric titration [ 14 ]. The analytical methods recommended in the Standard Method for the Examination of Water and Waste Water [ 15 ] and the Official and Standardized Method of Analysis [ 16 ] are: (1) argentometric titration with silver nitrate using potassium chromate indicator, (2) titration with mercuric nitrate using s-diphenylcarbazone indicator, and (3) potentiometric titration using a glass and a silver-silver chloride electrode.…”

Section: Introductionmentioning

confidence: 99%

“…Changes in pH during certain types of precipitation titrations have long been observed [ 12 , 27 , 28 ], and the pH change can be made large enough so that an equivalence point can be determined either potentiometrically with a pH electrode or using acid-base indicators under suitable conditions. When reactions involve hydrolysis of a cation or an anion yielding a large pH, an equivalence point can be detected potentiometrically [ 29 – 31 ].…”

Section: Introductionmentioning

confidence: 99%

“…Thus, very little change in pH (ΔpH < 0.1) has been observed around an equivalence point during a titration of chloride ion with silver ion [ 27 ]. In the presence of various adsorption indicators, however, somewhat larger changes in pH have been observed [ 12 , 28 ]; typically, ΔpH is less than three units. This change is not large enough for an acid-base indicator to respond sharply at the equivalence point although it can be followed potentiometrically with a pH meter [ 36 ].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Determination of Chlorinity of Water without the Use of Chromate Indicator

Hong

Kim²,

Czae

2010

International Journal of Analytical Chemistry

View full text Add to dashboard Cite

A new method for determining chlorinity of water was developed in order to improve the old method by alleviating the environmental problems associated with the toxic chromate. The method utilizes a mediator, a weak acid that can form an insoluble salt with the titrant. The mediator triggers a sudden change in pH at an equivalence point in a titration. Thus, the equivalence point can be determined either potentiometrically (using a pH meter) or simply with an acid-base indicator. Three nontoxic mediators (phosphate, EDTA, and sulfite) were tested, and optimal conditions for the sharpest pH changes were sought. A combination of phosphate (a mediator) and phenolphthalein (an indicator) was found to be the most successful. The choices of the initial pH and the concentration of the mediator are critical in this approach. The optimum concentration of the mediator is ca. 1~2 mM, and the optimum value of the initial pH is ca. 9 for phosphate/phenolphthalein system. The method was applied to a sample of sea water, and the results are compared with those from the conventional Mohr-Knudsen method. The new method yielded chlorinity of a sample of sea water of (17.58 ± 0.22) g/kg, which is about 2.5% higher than the value (17.12 ± 0.22) g/kg from the old method.

show abstract

Adsorption Indicators

Cited by 2 publications

References 55 publications

The partition of salts (i) between two immiscible solution phases and (ii) between the solid salt phase and its saturated salt solution

The partition of salts (i) between two immiscible solution phases and (ii) between the solid salt phase and its saturated salt solution

Determination of Chlorinity of Water without the Use of Chromate Indicator

Contact Info

Product

Resources

About