Potentiometric determination of solubility product constants: A laboratory experiment

A modified laboratory experiment for undergraduate students is presented to evaluate the effects of the ionic strength, I, on the equilibrium concentration quotient, K c, of the acid–base indicator bromcresol green (BCG). The two-step deprotonation of the acidic form of the dye (sultone form), as it is dissolved in water, yields suitable hydronium concentration in the solution to carry out the experiment successfully and avoids the use of any buffer solution to fix the hydronium concentration of the media. The 95% confidence interval for the slope parameter (−2.08 ± 0.13), obtained from the linear fit of pK c versus √I/ (1 + 2.30·√I) plot, contains the theoretical value of −2.04 predicted by the Debye–Hückel extended law. From the intercept, a value for the equilibrium dissociation constant of BCG, pK = (4.91 ± 0.02), is obtained, showing a reasonable agreement with literature data. The simplification makes it possible for students to complete the experiment in the course of an ordinary 3-h laboratory session.

mentioning

confidence: 99%

A Simplified Undergraduate Laboratory Experiment To Evaluate the Effect of the Ionic Strength on the Equilibrium Concentration Quotient of the Bromcresol Green Dye

Rodríguez¹,

Mirenda

2012

“…Indeed, various reports highlight the potentiometric measurements of solubility products of silver salts and their applicability as an undergraduate laboratory experiment. − Typically a potentiometric cell includes a silver wire that monitors the activity of Ag + (aq). The indicator and the reference electrodes are placed in two beakers separated by a salt bridge.…”

Section: Introductionmentioning

confidence: 99%

“…= °+ a e (at 25.0 C) E Ag 0.555/0.0257 cell (6) Assembling an electrochemical cell as presented in the cell notation and measuring the cell emf on a digital voltmeter facilitate the quantification of a Ag + .…”

Section: ■ Introductionmentioning

confidence: 99%

Feasibility of Using a Multicompartment Electrochemical Cell for Determination of Solubility Product Constants of Silver Salts from Potentiometric Measurements: A Directed Study in the Undergraduate Physical Chemistry Laboratory

Onbey,

Stringfellow,

Dabke

et al. 2023

The use of a multicompartment electrochemical cell for the potentiometric determination of solubility product constants of aqueous I − , Br − , SCN − , and Cl − salts of silver is presented. An electrochemical cell presented in this study contained multiple half-cells made of disposable drinking straws, a silver wire electrode housed in a plastic syringe, and a reference electrode. An agreement between the solubility product constant values of AgI, AgBr, AgSCN, and AgCl obtained by the students (7.84

“…Several undergraduate laboratory experiments determining solubility or a solubility product have been proposed. Most commonly, a saturated solution is prepared and one of its components is determined by gravimetric, volumetric, spectroscopic, spectrophotometric, or radiochemical techniques. − Some experiments use potentiometric cells, but do not yield titration curves and require an assumed E o value. ,− Two experiments give one of the curves. , Many suffer from toxicity or radioactivity concerns. − ,,,,,, None appears to have become a standard undergraduate experiment.…”

mentioning

confidence: 99%

A Simple Determination of the Ag₂O Solubility Product by Potentiometric Determinations of Both Ag⁺¹ and OH^–1

Sauls

2013

A simple determination of the Ag 2 O solubility product, K sp , suitable for introductory, analytical, or physical chemistry courses is presented. Two pH meters are required and 10 -4 mol of AgNO 3 or AgOAc is consumed. The concentration cell, Ag(s) | Ag + (0.001 M) || Ag + (0.001 M) {pH electrode} | Ag(s), is used. The cell potential and pH are monitored as standard 0.1 M NaOH is titrated into the cathode compartment, precipitating Ag 2 O. The cathode pOH, pAg, and pK sp are computed at each point of the titration. The results illustrate theoretical expectation and are in excellent agreement with the literature.