Nernst plots and formal potentials in a nonpolar solvent consisting of aluminum bromide (Al2Br6) and potassium bromide in ethylbenzene

Abstract

Nernst plots and formal potentials were determined for four metals (Pb, Sn, Cu, Ag). The two divalent ions (Sn, Pb) yield the expected slope of 2.3RT/2F. A maximum is observed when the concentration of the salt approaches that of free A1,Br6. This is accounted for quantitatively in terms of the various ionic species, i.e. [M(A12Br,)]+, [M(AI,Br,),]-and [M(AlBr4)]+, [M(AIBr,),]-for a divalent metal (M), which can be stable in this nonpolar solvent system. Copper is found to occur in solution only in the monovalent state, even when CuBr, is dissolved. The Nernst slope is (5/6)(2.3RT/F), which is consistent with the participation of both the positive ( [Cu2(AI2Br7)]+ or [Cu,(AIBr,)]+) and negative ([Cu(AI,Br,),]-or [Cu(AlBr,),]-) complex ions in setting the equilibrium at the interface.For silver a Nernst slope of 2.3RT/F is observed. Oxidation of lead or tin to the tetravalent state was not observed in the range of potential available up to bromine evolution. When CuBr, was dissolved, a disproportionation reaction took place, with formation of free bromine and monovalent copper, as evidenced by the appearance of the bromo derivative of the solvent. A listing of formal potentials, measured here and in earlier publications, shows that the scale of emf values is considerably compressed compared to that of aqueous solutions (from 2.75 V to 1.5

Arene Complexes of Divalent Tin Bromoaluminates

“…[12] Additionally, some interesting compounds have already been synthesized and structurally characterized with [AlBr 4 ]or [Al 2 Br 7 ] -, among them the 2-norbonyl cation, [13] the room temperature ionic liquid [(CH 3 ) 3 C][Al 2 Br 7 ], [14] and various protonated arenes. [15] However, to the best of our knowledge, apart from electrochemical investigations, [16] no further synthetic study was made and no crystal structure is known of any such compound. Therefore, we investigated the reaction between tin(II) bromide and aluminium bromide in different solvents and the findings of these reactions are presented herein.…”

Cyclic Voltammetry in Solutions of Aluminum Bromide and KBr in Aromatic Hydrocarbons: III . The Behavior of Ag and Cu

“…The average slope dEJd log C shown in Fig. 5 is 58 -+ 2 mV/decade, to be compared with a value of 49 -+ 1 mV/decade reported in our earlier publication (9). The potential difference AE = Ep -Ep/.o, which should be equal to 20 mV for a reversible, one-electron process, exhibits a behavior similar to that shown above for AgBr, increasing slightly with sweep rate from 10 to 20 mV and decreasing with concentration of CuBr.…”

“…Although the nucleation overpotentia] for silver deposition on clean platinum is relatively small (11), as indicated by the narrow overpotential range where a current maximum occurs in the pulse potentiostatic curves, it could be the cause of the discrepancies noted above. It should also be noted that different electroactive species may occur in this system (9,12) giving rise to various reaction mechanisms occurring simultaneously, leading to unusual values of the observed diagnostic parameters. for two sweep rates.…”

“…However, E,~2 depends on the concentration of AgBr (dEp/Jd log C = 63 -* 4 mV/decade), as would be expected for a one-electron reversible metal deposition process. Measurements of the reversible potential as a function of concentration yielded a Nernst slope of 57 mV/decade (9). A further anomaly is found when the difference between the cathodic peak potential [Ep(c)] and the cathodic half-peak potential [Epj~(c)] is considered.…”

Review on Detection of Phenol in Water

“…The complete non-polar solvents namely benzene or various hydrocarbons are employed for studying solution phase [84] and surface processes [85]. Some brief explanation for the solvent applied in the electrochemistry is presented [86].…”