The application of hydrogen-palladium electrode for potentiometric acid-base determinations in tetrahydrofuran

Abstract

The application of the hydrogen-palladium electrode (H2/Pd) as the indicator electrode for the determination of relative acidity scale (Es, mV) of tetrahydrofuran (THF) and the potentiometric titrations of acids in this solvent was investigated. The relative acidity scale tetrahydrofuran was determined from the difference half-neutralization potentials of perchloric acid and tetrabutylammonium hydroxide (TBAH), which were measured by using both H2/Pd-SCE and glass-SCE electrode pairs. The experimentally obtained value of Es scale THF with a H2/Pd-SCE electrode pair was 1155 mV, and those obtained with glass-SCE electrode pair 880 mV. By using a H2/Pd indicator electrode, the individual acids (benzoic acid, palmitic acid, maleic acid, acetyl acetone, α-naphthol) and two component acid mixtures (benzoic acid + α-naphthol, palmitic acid + α-naphthol, maleic acid + α-naphthol and maleic acid + ftalic acid) were titrated with a standard solution of TBAH. In addition, sodium methylate and potassium hydroxide proved to be very suitable titrating agents for titrating of the individual acids and the acids in mixtures, respectively. The relative error of the determination of acids in mixture was less than 3%. The results are in agreement with those obtained by a conventional glass electrode. The advantages of H2/Pd electrode over a glass electrode in potentiometric acid-base determinations in tetrahydrofuran lie in the following: this electrode gives wider relative acidity scale THF, higher the potential jumps at the titration end-point and relatively fast response time; furthermore, it is very durable, simple to prepare and can be used in the titrations of small volumes. [Projekat Ministarstva nauke Republike Srbije, br.172051

Synthesis of a Novel Sensor Electrode Based on Bromothymol Blue as an Indicator Electrode in Potentiometric Acid-Base Titration in Aqueous Solution

“…Different types of electrode have been used as acid-base indicator electrodes. Of those, the most frequently used are the titanium, hydrogen-palladium and other electrodes [9][10][11][12].…”

“…To study the thermal stability of the sensor, calibration graphs were constructed at different test solution temperatures 15, 25, 35 and 45 C. According to Figure 6. The sensor would be used for pH measurements in the range from (2)(3)(4)(5)(6)(7)(8)(9)(10)(11). At lower temperatures, like 283 K, the slope of the sensor was about 34.12 mV/decade.…”

A Spin Coating of Thymol Blue Indicator on F-SnO2 Glass to fabricate a Novel Sensor Electrode in Potentiometric Acid-Base Titration

“…The Thymol blue sensor response was evaluated at different temperatures, Figure 4. At lower temperatures, like 288K, the slope of the sensor was about 33.54mV/decade and the sensor would be used for pH measurements in the range from (2)(3)(4)(5)(6)(7)(8)(9)(10)(11). However, when the temperature of the test solutions was adjusted to 298K, the slope significantly increased to 53.11mV/decade.…”

“…Titrimetric procedures based on a detection of the endpoint, i.e., the point at which volumetric titration is completed, are successfully employed over a wide range of concentrations and are popular because of their simplicity, speed, accuracy and good reproducibility [9]. Recently, many studies developed some types of electrodes in potentiometric acid base titration [10][11][12][13]. Thymol blue (thymolsulphonephthalein) is used as a pH indicator.…”