Nickel wire

FIG. 8-61 Typical resistance-thermometer curves for platinum, copper, and nickel wire, where Rj = resistance at temperature T and Rq = resistance at 0 C. 

Figure 3 is a sketch made at the start of an experiment4,14 with a fresh piece of carbon. Clearly, the fresh carbon piece is wet by the molten KF-2HF. Figure 4 is a sketch of the same system a few minutes after the carbon is made anodic by applying 5 V between the carbon block and a piece of nickel wire in the KF-2HF electrolyte. The CFX layer forms (see Fig. 2) and is not wet by the KF-2HF. In fact, the KF-2HF forms a ball and behaves like water on clean polytetrafluoroethylene or mercury on clean glass. (The contact angle has been estimated10 to be 140°.)... 

C04-0039. Predict whether or not a reaction will occur, and if a reaction does take place, write the half-reactions and the balanced redox reaction (a) a strip of nickel wire is dipped in 6.0 M HCl (b) aluminum foil is dipped in aqueous CaCl2 (c) a lead rod is dipped in a beaker of water (d) an iron wire is immersed in a solution of silver nitrate. 

C19-0128. A galvanic cell is constructed using a silver wire coated with silver chloride and a nickel wire immersed in a beaker containing 1.50 X 10 M NiCl2 (a) Determine the balanced cell reaction, (b) Calculate the potential of the cell, (c) Draw a sketch showing the electron transfer reaction occurring at each electrode. 

A supporting conductive structure, made of a nickel-wire woven net, silver-plated in order to minimise corrosion of the substrate arising from the operating conditions, and able to distribute the current uniformly all over the surface. 

The use of several different experimental techniques to investigate a given system is likely to be particularly revealing. Two noteworthy examples in which stereochemical considerations had a part are provided by Taylor and Dibeler (8) on the reactions of deuterium with the butenes on nickel wires and by Meyer and Burwell (9, 10) on the deuteration of multiply unsaturated hydrocarbons. 

Heating a nickel wire to elevated temperatures in vacuum increases the catalytic activity of the wire for the decomposition by several orders of magnitude (89). 

In [53], oscillatory wave patterns observed during electrochemical dissolution of a nickel wire in acidic media was reported. It was shown that space-averaged potential or current oscillations are associated with the creation of an inhomogeneous current distribution, and that the selection of a specific spatial current pattern depends on the current control mode of the electrochemical cell. In the almost potentiostatic (fixed potential) mode of operation, a train of traveling pulses prevails, whereas antiphase oscillations occur in the galvanostatic (constant average current) mode. 

In a few cases, adsorption on particulate nickel has been studied other than in the form of the conventional oxide-supported metal catalysts. Nash and De Sieno (73) exploded nickel wires in a rare-gas atmosphere to give Ni particles of ca. 20-nm diameter. Results were reported (but not illustrated) characterizing adsorption of ethyne they are similar to those found by Eischens and Pliskin. 

Fig. 11. Distribution of (a) deuteroethylene yields and (b) deuteroethane yields as a function of conversion observed in the reaction of ethylene with deuterium over a nickel wire at 90°C [91],...

One of the earliest studies of the reaction of C2H4 with D2, in which a full mass spectrometric analysis of the products was performed, used a nickel wire as catalyst [115,116]. Some typical results are shown in Fig. 11. These results showed that ethylene exchange was rapid and the deutero-ethylenes are probably formed in a stepwise process in which only one deuterium atom is introduced during each residence of the ethylene molecule on the surface, that is there is a high probability of ethylene desorption from the surface. From Fig. 11(a) it can also be seen that the major initial products are ethane-d0 and ethane-d,. This is consistent with a mechanism in which hydrogen transfer occurs by the reaction... 

One of the earliest studies of n-butene hydrogenation was that reported by Twigg [121] who observed that, for the reaction of l butene with hydrogen over a nickel wire between 76 and 126°C, both hydrogenation and double-bond migration occurred. Hydrogenation and double-bond migration followed the same kinetic rate law, namely... 

Activation energies for butene hydrogenation and isomerisation over a nickel wire catalyst [122]... 

Fig. 1. Section of disk-type cell where 1 is the cell cup 2, the bottom insert 3, the separator 4, the negative electrode 5, the positive electrode 6, the nickel wire gauze 7, the sealing washer 8, the contact spring and 9, the cell cover...

The electrochemical window of pure molten cryolite has not been expressly stated, but a voltammogram of purified cryolite recorded at a graphite working electrode exhibits very little residual current over the range of potentials extending from 0.4 to -1.9 V vs. a nickel wire quasi-reference electrode [7]. Physical property data for molten cryolite and phase equilibria for the AlF3-NaF melt system have been summarized [31,32]. The extremely high temperature of cryolite places severe constraints on the materials that can be used for cells. Platinum and boron nitride are the materials of choice. 

In view of the nature of the catalyst, the pretreatment, the reaction temperature range, the very large specific conversion rate, and the positive temperature coefficient it may be concluded that the reaction studied by Justi and Vieth was not the nondissociative conversion. Furthermore, Schwab and Kaiser (29) reported that they had been unable to confirm the Justi and Vieth results (over nickel wire). The writer (30) found no field effect for the conversion at 298 K greater than 0.5% over pretreated nickel wire up to 4 kOe. It is necessary to conclude that the Justi and Vieth work is of no significance insofar as the present paper is concerned, and also that there is doubt concerning the reality of their results. 

The writer (30) has also attempted to measure the extrinsic field effect over pretreated nickel wire, and over nickel supported on silica gel, at 77... 

Dimethyl benzene Apiezon Preconcentration on Apiezon L coated nickel wire then Curie point pyrolysis-GC [210]... 

Place in separate clean, dry test tubes (100 x 13 mm) 2 mL of distilled water and 2 mL of the residue liquid from the boiling flask. Obtain a clean nickel wire from your instructor. In the hood, dip the wire into concentrated nitric acid and hold the wire in a Bunsen burner flame until the yellow color in the flame disappears. Dip the wire into the distilled water sample. Put the wire into the Bunsen burner flame. Record the color of the flame. Repeat the above procedure, cleaning the wire, dipping the wire into the liquid from the boiling flask, and observing the color of the Bunsen burner flame. Record your observations. Sodium ions produce a bright yellow flame with a Bunsen burner. 

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