Thallium amalgam

Reference Electrodes and Liquid Junctions. The electrical cincuit of the pH ceU is completed through a salt bridge that usually consists of a concentrated solution of potassium chloride [7447-40-7]. The solution makes contact at one end with the test solution and at the other with a reference electrode of constant potential. The Hquid junction is formed at the area of contact between the salt bridge and the test solution. The mercury—mercurous chloride electrode, the calomel electrode, provides a highly reproducible potential in the potassium chloride bridge solution and is the most widely used reference electrode. However, mercurous chloride is converted readily into mercuric ion and mercury when in contact with concentrated potassium chloride solutions above 80°C. This disproportionation reaction causes an unstable potential with calomel electrodes. Therefore, the silver—silver chloride electrode and the thallium amalgam—thallous chloride electrode often are preferred for measurements above 80°C. However, because silver chloride is relatively soluble in concentrated solutions of potassium chloride, the solution in the electrode chamber must be saturated with silver chloride. 

Mercury-switch thermostats, 16 42 Mercury-thallium amalgam, 24 628 Mercury thermometers, 24 464, 465 Mercury vapor intoxication, chronic, 16 51 Mercury vapor lamps, vitreous silica in, 22 441... 

Dropping indium and thallium amalgam electrodes [41] were used to determine kinetic parameters of Zn(II) reduction as a function of the amalgam composition. The formal potentials were shifted to more negative values with increasing thallium and indium amalgam concentrations. 

Propylene Carbonate (PC) and Water. Data from both spectroscopic and thermodynamic studies for other solvent systems are sparse and some of it is of doubtful quality. For propylene carbonate, Salomon (40) has obtained emf data using lithium metal and thallium amalgam-thallous chloride or bromide electrodes. 

Hg Tl (liq.). The values for the liquid thallium amalgams are from Richards and Daniels1 and Richards and Smith.2... 

TI+/TI(Hg) electrode — A -> reference electrode commonly known as Thalamid electrode employing thallium amalgam (40wt%) as electronically conducting phase and an aqueous solution of KC1 (saturated or 3.5 M) saturated with T1C1. In comparison with the saturated calomel electrode it shows a superior temperature stability up to T = 135 °C without temperature hysteresis, no disproportionation of T1C1 (as compared to Hg2 CI2) or significant complexation are found. 

The solution to the right of the glass electrode is usually a buffer solution of KH2P04 and Na2HP04, with 0.1 mol dm"3 of NaCl. The reference electrode is usually a calomel electrode, silver/silver chloride electrode, or a thallium amalgam/thallous chloride electrode. The emf of this cell depends on a(H + ) in the solution X in the same way as that of the cell with the Pt H2 electrode, and thus the same procedure is followed. 

TABLE XXVIII. ACTIVITY OF MERCURY IN THALLIUM AMALGAMS AT... 

To illustrate the application of equation (38.33) to calculate the activity or activity coefficient of one constituent of a solution when that of the other is known, use may be made of the results for the thallium amalgams given in 38e. The values of a2/N2 for thallium at various compositions are available (Table XXVII), and the data required for the evaluation of the... 

The vapor pressures of mercury in equilibrium with thallium amalgams containing various mole fractions (Ni) of mercury at 26 C were found to be as follows [Hirst and Olson, J. Am. Chem. Soc.y 51, 2398 (1929)] ... 

Consider equations (38.33) and (38.24) and hence indicate how ai/Ni for mercury could be determined directly, by a graphical method, from the e.m.f. data on the thallium amalgam cells in Table XXVII. 

Low-temperature thermometers (8.5% thallium amalgam melting point -58°G). 

Thus, thallium ion discharge on thallium amalgam was investigated, using the impedance method, by Randles, and it was shown that log ks changes linearly with the change of the reversible potential as indicated by Eq. (25). The plot rendered (3 = 0.52 (similar results were obtained from Faradaic rectification measurements by Barker et... 

Fleischmann, M., Pattison, J. and Thirsk, H.R. (1965) ElectrocrystaUisation of thin films of thallous chloride on thallium amalgam. Transactions of the Faraday Society, 61, 1256. 

Thallium electrode is a second-kind electrode composed of thallium amalgam (40 %) and a thallium salt, most often thaUium(I) chloride, but also thallium(l) bromide or sulfate can be used [148, 149] ... 

It is interesting to compare these data with the data for thallium amalgam, for which the change in solubility of T1 with temperature is small[403], and hence we can expect that the distortions in the temperature dependence are small. Indeed, it was described in section 4.4 that the preexponential factor and the isotope effect for such a cathode are in good agreement with each other and with the results for several pure metals. 

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