Nickel masking

Show that CN is an appropriate masking agent for Nb+ in a method in which nickel s complexation with EDTA is an interference. 

Inhalation of extremely fine carbide, cobalt, and nickel powders should be avoided. Efficient exhaust devices, dust filters, and protective masks are essential when handling these powders. 

Sometimes the metal may be transformed into a different oxidation state thus copper(II) may be reduced in acid solution by hydroxylamine or ascorbic acid. After rendering ammoniacal, nickel or cobalt can be titrated using, for example, murexide as indicator without interference from the copper, which is now present as Cu(I). Iron(III) can often be similarly masked by reduction with ascorbic acid. 

The procedure utilises eriochrome blue black RC (also called pontachrome blue black R Colour Index No. 15705) at a pH of 4,8 in a buffer solution. Beryllium gives no fluorescence and does not interfere iron, chromium, copper, nickel, and cobalt mask the fluorescence fluoride must be removed if present. The method may be adapted for the determination of aluminium in steel. 

Scheme 13). The addition product 53 was reduced to diol 54, and Raney nickel was used for the removal of the masking group. 

Both characteristic X-ray line and continuous spectra were used to evaluate the performances of the resists. To determine exposure parameters (i.e. sensitivity and contrast) irradiations were carried gut in this study using the aluminum Kot- 2 emission line at 8.3t A generated by means of a modified Vacuum Generators Limited model EG-2 electron beam evaporation gun. The resist samples were exposed through a mask (A) consisting of a range of aluminum foils of different thicknesses supported on an absorbing nickel frame in order to vary the X-ray flux. 

Several ions (e.g., manganese, iron (II), iron (III), cobalt, nickel, copper, zinc, cadmium, lead, and uranyl) react with pyrocatechol violet, and to some extent are extracted together with aluminium. The interferences from these ions and other metal ions generally present in seawater could be eliminated by extraction with diethyldithiocarbamate as masking agent. With this agent most of the metal ions except aluminium were extracted into chloroform, and other metal ions did not react in the amounts commonly found in seawater. Levels of aluminium between 6 and 6.3 pg/1 were found in Pacific Ocean and Japan Sea samples by this method. 

The cyclic voltammogram of complex 3 B"-Ni shows two quasi-reversible Ni(0)/(I) and Ni(I)/(II) redox waves at —2.5 V and —I.IV vs. Fc/Fc, respectively. Neither of the two oxidized complexes was isolable, most likely due to the masking of the low-valent nickel(O) center by the three ter -butyl substituents on the carbene ligand. The search for alternative routes to these complexes using less sterically bulky NHC ligands, such as the TIMEN isopropyl derivative, is under investigation. 

This might alter the electric field of the metal or that experienced by the incoming hydrocarbon, leading to enhanced dehydrogenation on the metal site, and cyclization on the nearby acid sites. Neither of the first two routes would be expected to increase the activity associated with vanadium, since vanadium is much more mobile than nickel, and appears to remain as V + in these systems (Schubert, P. F. Altomare, C. A. Koermer, G. S., Engelhard Corporation Willis, W. S. Suib, S. L., University of Connecticut, manuscript in preparation). While vanadium might be expected to be affected by proximity to the zeolite, this effect could be masked by the destruction of the zeolite. 

Nickel chloride is used in nickel electroplating baths. It also is used to prepare various nickel salts and nickel catalysts and in industrial gas masks to protect from ammonia. 

Considerable inter-element interference effects have been reported on the actual hydride-forming step. Elements easily reduced by sodium borohydride (e.g. silver, gold, copper, nickel) give rise to the greatest suppressions. These interfering ions may be removed by the addition of masking agents that complex with them. 

Earlier work on the exchange of methylcyclopentane and methylcyclo-hexane over nickel catalysts at 150°-200° had not shown any discontinuities in the distribution pattern of the products (S9). There was a uniform rise up to a maximum for the fully deuterated species. This is not surprising, since similar behavior was noted with cyclopentane and cyclohexane under the same conditions. At these high temperatures the interchange reaction occurs sufficiently readily to mask any division of the hydrogen atoms into sets. 

Preparation of Bismuth and Studying of Its Properties. (Perform the experiment in the presence of your instructor, wear eye protection or a protective mask ) Prepare bismuth by reducing 0.5 g of bismuth(lll) oxide with hydrogen similar to the preparation of metallic nickel or iron. Perform the reduction at 240-270 °C. 

A secondary, more subtle, effect that can be utilized in the achievement of selectivity in cation exchange is the selective complexation of certain metal ions with anionic ligands. This reduces the net positive charge of those ions and decreases their extraction by the resin. In certain instances, where stable anionic complexes form, extraction is suppressed completely. This technique has been utilized in the separation of cobalt and nickel from iron, by masking of the iron as a neutral or anionic complex with citrate350 or tartrate.351 Similarly, a high chloride concentration would complex the cobalt and the iron as anionic complexes and allow nickel, which does not form anionic chloro complexes, to be extracted selectively by a cation-exchange resin. 

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