Potentiometric titrations in non-aqueous solution

Heijde, H.B. van der

doi:10.1016/s0003-2670(00)89954-7

Cited by 49 publications

(8 citation statements)

References 6 publications

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“…Occasionally the titration curves obtained show peculiar inverted inflections which tend to obscure normal inflections and make interpretation difficult. Similar irregularities have been reported by van der Heijde (11), who explained them on the basis of insufficient solvation of the highly polar acid molecules and their ions by inert or weakly basic solvents. The incomplete solvation causes solutes to be adsorbed onto electrode surfaces, and this in turn Figure 1.…”

supporting

confidence: 85%

“…In a similar manner potassium ion contamination may occur in the nonaqueous ion exchange method of Harlow, Noble, and Wyld (8). Since van der Heijde (11) used this method of preparation, some of the anomalous inflections w'hich he observed may have been due to potassium ion in this titrant. Both of the methods described above will result in titrants with a negligible alkali ion concentration, if proper care is taken during preparation or purification.…”

Section: Discussionmentioning

confidence: 99%

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Potentiometric Titration of Very Weak Acids. Effect of Potassium on the Glass Electrode

Harlow¹

1962

Anal. Chem.

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supporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Potentiometric Titration of Very Weak Acids. Effect of Potassium on the Glass Electrode

Harlow¹

1962

Anal. Chem.

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“…In solvents such as acetone, acetonitrile, and pyridine, the titration curves have a steep slope in the buffered region, owing to the intermolecular association of the acid anion with the free acid (4,10,16,17). Evidently, this association is not appreciable in tertiary butyl alcohol.…”

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confidence: 99%

Acid-Base Equilibria in Tertiary Butyl Alcohol.

Marple¹,

Fritz²

1963

Anal. Chem.

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The dissociation of acids in tertiary butyl alcohol has been studied by potentiometric, spectrophotometrie, and conductimetric methods. Values for the overall dissociation of perchloric and picric acids and several tetrabutylammonium salts were estimated by the Puoss-Kraus treatment of conductance data. Potent iometric stales were carried out at constant ionic strength in order to minimize activity coefficient variations. An acidity scale was established from potenciometric measurements at a glass electrode, and conductance values of dissociation constants. A method was developed for the evaluation of the overall dissociation constant of weak acids using potentiometric data for hydrogen ion activities and conductance data for the corresponding anion activities. Overall dissociation con stants are reported for perchloric acid, picric acid, 2,4-dinitrophenoI, and benzoic acid. Apparent dissociation constants from potentiometric measurements at a constant ionic strength were determined for hydrobromic, nitric, hydrochloric, picric, and p-toluenesulfonic acids. Contribution Bo. 1205. Work was performed in the Ames Laboratory of the U. S. Atomic Energy Coamission. Tertiary butyl alcohol has been shown to be * very u*eful solvent for the titration of weak acids with tetrabutylaamnluM hydroxide (14). This solvent is especially useful for differentiating titrations in volving carboxylic acids and phenols because of the flat slope in tike buffer region of the titration curve. In solvents such as acetone, acetonitrile, and pyridine, the titration curves have a steep slope In the buffered region, owing to the intenaolecular association of the acid anion with the free acid (4,10,16,17). Evidently, this association is not appreciable in tertiary butyl alcohol. Because of its excellent solvent characteristics, fundamental information on acid-base equilibria would be very useful. Taking into account previous investigations of acid-base equilibria in alcoholic solvents (1,2,11,12,13,15) and solvents of low dielectric constant (9*6), we felt that the main reactions involved in the dissociation of an acid HX are: HX ^ H+X (ion-pair formation); H+X~ ^ ♦ X~ (ion-pair disso ciation). The corresponding equilibrium constants are: * (H*X~)/(HX) Kd * (H)(x")/(hV). Ion-pair formation in tertiary butyl alcohol is undoubtedly significant (6), bt.t probably not extensive. The overall dissociation of strong electrolytes in dilute solutions (lO'^M to lCf^M) was expected to be large on the basis of titration data.

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“…In terms of aqueous pH, Equation 10becomes, for a strong base, pH* = y, pHw -7 + y2 log Klog Ks - Unfortunately, the simple dissociation HA = H+ + Ais not the only common process in nonaqueous solvents. At moderate acid concentrations, the reaction 2HA ^H+ + HA2 = (H+) (HA,-) _ (H+)2 (HA)2 _ (HA)2 (14) was found to be predominant in many systems (14,15,18,21,24,28,(31)(32)(33)(34). Similar processes are known for bases (16, 26):…”

mentioning

confidence: 68%

Correlation between Apparent pH and Acid or Base Concentration in the ASTM Medium

Popovych¹

1964

Anal. Chem.

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Potentiometric titrations in non-aqueous solution

Cited by 49 publications

References 6 publications

Potentiometric Titration of Very Weak Acids. Effect of Potassium on the Glass Electrode

Potentiometric Titration of Very Weak Acids. Effect of Potassium on the Glass Electrode

Acid-Base Equilibria in Tertiary Butyl Alcohol.

Correlation between Apparent pH and Acid or Base Concentration in the ASTM Medium

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