Reference electrodes saturated calomel

If the copper electrode is the indicator electrode in a potentiometric electrochemical cell that also includes a saturated calomel reference electrode... 

The electroreductive cyclization of the furanone 118 (R = -(CH2)4CH=CH— COOMe Scheme 36) using a mercury pool cathode, a platinum anode, a saturated calomel reference electrode, and a degassed solution of dry CH3CN containing -Bu4NBr as the electrolyte, gave the spirocyclic lactones 119 and 120 in a ratio 1.0 1.1 (Scheme 37)(91T383). 

These values are roughly constant across a range of electrolyte environments except where noted but the variations between alloys, heat treatment conditions, etc. creates a range for each metal. For some metals such as iron and steel the range is low ( 100 mV), but for lead, nickel, stainless steels a range is given. The corrosion potential is reported with respect to the saturated calomel reference electrode. 

Stainless steel pipes (buried in the ground) and the interiors of stainless steel heat exchangers have been successfully cathodically protected, but CP is rarely used for materials other than steel. The protection potential usually adopted for steel is —850 mV to the saturated calomel reference electrode. This varies with temperature and the presence of other aggressive species in the environment. 

Ey and E2 are the indicator electrodes. These may consist of a tungsten pair for a biamperometric end point for an amperometric end point they may both be of platinum foil or one can be platinum and the other a saturated calomel reference electrode. The voltage impressed upon the indicator electrodes is supplied by battery B (ca 1.5 volts) via a variable resistance Rs N records the indicator current. For a potentiometric end point Ey and E2 may consist of either platinum-tungsten bimetallic electrodes, or Ey may be an S.C.E. and E2... 

Apparatus. Use the apparatus of Section 14.7. The generator anode is of pure silver foil (3 cm x 3 cm) the cathode in the isolated compartment is a platinum foil (3 cm x 3 cm) bent into a half-cylinder. For the potentiometric end point detection, use a short length of silver wire as the indicator electrode the electrical connection to the saturated calomel reference electrode is made by means of an agar-potassium nitrate bridge. 

So-called combination electrodes may be purchased in which the glass electrode and the saturated calomel reference electrode are combined into a single unit, thus giving a more robust piece of equipment, and the convenience of having to insert and support a single probe in the test solution instead of the two separate components. 

Prepare an approximately 0.1 M silver nitrate solution. Place 0.1169 g of dry sodium chloride in the beaker, add 100 mL of water, and stir until dissolved. Use a silver wire electrode (or a silver-plated platinum wire), and a silver-silver chloride or a saturated calomel reference electrode separated from the solution by a potassium nitrate-agar bridge (see below). Titrate the sodium chloride solution with the silver nitrate solution following the general procedure described in Experiment 1 it is important to have efficient stirring and to wait long enough after each addition of titrant for the e.m.f. to become steady. Continue the titration 5 mL beyond the end point. Determine the end point and thence the molarity of the silver nitrate solution. 

Place the prepared copper acetate solution in the beaker and add 10 mL of 20 per cent potassium iodide solution. Set the stirrer in motion and add distilled water, if necessary, until the platinum plate electrode is fully immersed. Use a saturated calomel reference electrode, and carry out the normal potentiometric titration procedure using a standard sodium thiosulphate solution as titrant. 

Electrochemical equipment and cells used for these investigations have also been described previously. (8.9 ) Polycrystalline Ag (Johnson Matthey, 99.9%) was mechanically polished with alumina (Buehler) to a mirror finish and sonicated in triply distilled H20 before each run. All potentials were measured and are reported versus a saturated calomel reference electrode (SCE). 

The saturated calomel reference electrode is an example of a constant-potential electrode. A drawing and a photograph of a typical SCE available commercially are shown in Figure 14.4. It consists of two concentric glasses or tubes, each isolated from the other except for a small opening for electrical contact. 

In Nebraska, state regulations require that the chemical makeup of animal feed sold in the state be accurately reflected on the labels found on the feed bags. The Nebraska State Agriculture Laboratory is charged with the task of performing the analytical laboratory work required. An example is salt (sodium chloride) content. The method used to analyze the feed for sodium chloride involves a potentio-metric titration. A chloride ion-selective electrode in combination with a saturated calomel reference electrode is used. After dissolving the feed sample, the chloride is titrated with a silver nitrate standard solution. The reaction involves the formation of the insoluble precipitate silver chloride. The electrode monitors the decrease in the chloride concentration as the titration proceeds, ultimately detecting the end point (when the chloride ion concentration is zero). 

For cases directly comparable to the cyclization originating from (27) above, the yields of the product were not as high. However, a related reaction used in the synthesis of an 11-substituted dibenzo[a,d]-cycloheptenimine derivative was very successful as shown in Scheme 11 (Eq. 2) [32]. In this reaction, a controlled potential electrolysis of (33) led to the formation of the tetracyclic (34) in an 85% isolated yield. The reaction was performed on a 1 g scale using an undivided cell, a graphite felt anode, a stainless steel cathode, a saturated calomel reference electrode, and a 1% NaBF4 in 70 30 THF/water electrolyte solution. The electrolysis was scaled up further with the use of a flow cell. In this experiment, 200 g of (33) were oxidized in order to afford a 75% isolated yield of (34). 

Unless otherwise stated, most studies were performed by cyclic voltammetry with freshly polished glassy carbon working electrode (GC) and a saturated calomel reference electrode (SCE). 

As the superconductor dissolves, Cul2 and I3" are carried within tens of milliseconds past the Pt ring electrode. In the potential range +0.2 to -0.5 V (vs. a saturated calomel reference electrode) a current near -0.1 mA flows due to reduction of the I3" at the Pt ring ... 

The detector cell was a three-electrode system consisting of a flow-through nickel working electrode, a saturated calomel reference electrode (SCE), and a stainless steel outlet tubing counter electrode. The tubular-type electrode cell housing was constructed of molded Teflon, which was machined to provide the channels and to accommodate the fittings. The working electrode area was... 

For ferroin, with E° = 1.147 V (Table 16-2), we expect the color change to occur in the approximate range 1.088 V to 1.206 V with respect to the standard hydrogen electrode. With a saturated calomel reference electrode, the indicator transition range will be... 

MeCN/CH2Cl2/aqueous 0.025 M sodium perchlorate, 90 5 5 Amperometric detection (reductive mode), silver electrode, — 1.1 V vs saturated calomel reference electrode... 

The vertical axis is in volts relative to the saturated calomel reference electrode (SCE). Photoemission in aqueous media is best performed in the electrochemical window, between the hydrogen and oxygen evolution redox potentials, where small dc currents allow easier detection of the photoemission current. Protons are used for scavenging the... 

For most potentiometric measurements, either the saturated calomel reference electrode or the silver/silver chloride reference electrode are used. These electrodes can be made compact, are easily produced, and provide reference potentials that do not vary more than a few mV. The silver/silver chloride electrode also finds application in non-aqueous solutions, although some solvents cause the silver chloride film to become soluble. Some experiments have utilised reference electrodes in non-aqueous solvents that are based on zinc or silver couples. From our own experience, aqueous reference electrodes are as convenient for non-aqueous systems as are any of the prototypes that have been developed to date. When there is a need to exclude water rigorously, double-salt bridges (aqueous/non-aqueous) are a convenient solution. This is true even though they involve a liquid junction between the aqueous electrolyte system and the non-aqueous solvent system of the sample solution. The use of conventional reference electrodes does cause some difficulties if the electrolyte of the reference electrode is insoluble in the sample solution. Hence, the use of a calomel electrode saturated with potassium chloride in conjunction with a sample solution that contains perchlorate ion can cause dramatic measurements due to the precipitation of potassium perchlorate at the junction. Such difficulties normally can be eliminated by using a double junction that inserts another inert electrolyte solution between the reference electrode and the sample solution (e.g., a sodium chloride solution). 

Single electrochemical measurements are carried out with a PAR model 283 potentiostat (Princeton Applied Research) controlled by the CorrWare software (Ametek, France) or an Autolab Metrohm potentiostat controlled by the General Purpose Electrochemical System software (Metrohm, France). VMP2/Z multipotentiostat controlled by the ECLab software (Ametek, France) is used for several simultaneous measurements. All electrochemical experiments involve a saturated calomel reference electrode (SCE) (Radiometer, France) and a large-surface-area platinum disk as counter-electrode. 

The three electrodes the working microelectrode, the saturated calomel reference electrode and the platinum auxiliary electrode are immersed in a 5 mmol L-1 deaerated ferricyanide solution. 

The saturated calomel reference electrode, the platinum counterelectrode and one or several working microelectrodes are placed directly on the skin surface, without adding water or gel. The saturated calomel reference electrode is connected to the skin by a felt-tip pen used as a Luggin capillary. The distance between all electrodes is less than 1cm. 

The potential of steel in a test solution at 25 °C was measured with a saturated calomel reference electrode (SCE) and found to be +34 mV. 

EDTA). In this application the M(OH2)l+ cation that is to be titrated forms a soluble EDTA complex that is appreciably less stable than the HgEDTA complex.141 The mercury electrode is constructed in a form like that of Figure 5.40a or b, and is used in conjunction with a saturated calomel reference electrode. The electrode is immersed in a solution that contains the ion to be titrated [M(OH2) +], and a few drops of 0.01 M HgY2- are added (where Y4-represents the EDTA anion). This establishes the potential of the mercury electrode according to the half-cell reaction... 

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