Nickel gravimetric analysis

Carmosini, N. Ghoreshy, S. Koether, M. C. The Gravimetric Analysis of Nickel Using a Microwave Oven, ... 

Whether prepared from a homogeneous (excess ethanol is required) or a nonhomogeneous medium, the orthoformate derived dichloro(l,2-dimethoxyethane)nickel(II), on thermo-gravimetric analysis (heating at 10°C. min-1) begins to lose its ligand at 91°. The loss proceeds in two stages the first, 28%... 

Nickel forms a red chelate with dimethylglyoxime (DMG), which is quite suitable for gravimetric analysis. Precipitation of the chelate is complete in an acetic acid-acetate buffer or in an ammoniacal solution. Acetate buffer is generally used when Zn, Fe, or Mn is present in the alloy. The sample given to you is a nichrome alloy that has Ni (approximately 60%), Cr, and Fe as the major constituents. Interference from Cr and Fe is removed by complexation with tartrate or citrate ions. Precipitation is then carried out in an ammoniacal solution. The Ni content is calculated from the weight of the precipitate (see Table 10.2 for the formula). 

The red square planar complex bis(dimethylglyoximato)-nickel(II), [Ni(Hdmg)2] (Figure 21.28a), is used for gravimetric analysis of nickel Ni(II) is precipitated along with Pd(II) when the ligand H2dmg in weakly ammoniacal... 

Hic purity partially sintered nickel sheets were obtained from ERC (Electric Research Ciorp.). The porosity of these sheets varied firom 60% to 70%. The proprietary nature of these materials prohibits any release of the pore size distribution. Disks with a thickness of 30 mils and a diameter of 11/4" were cut from this material. This disks were soaked in 1 molar liOH, dried at 100X1, and oxidized in room air at 650 C for at least 8 hours to form a lithiated NiO stmcture. Gravimetric analysis of these electrodes showed that they were greater than 98% converted to NiO. 

Various other reagents are also useful for gravimetric analysis, for example dimethylglyoxime (a) for nickel and oxine (b) for aluminum and magnesium (Fig. 2(a) and (b)). 

Nickel also is deterrnined by a volumetric method employing ethylenediaminetetraacetic acid as a titrant. Inductively coupled plasma (ICP) is preferred to determine very low nickel values (see Trace AND RESIDUE ANALYSIS). The classical gravimetric method employing dimethylglyoxime to precipitate nickel as a red complex is used as a precise analytical technique (122). A colorimetric method employing dimethylglyoxime also is available. The classical method of electro deposition is a commonly employed technique to separate nickel in the presence of other metals, notably copper (qv). It is also used to estabhsh caUbration criteria for the spectrophotometric methods. X-ray diffraction often is used to identify nickel in crystalline form. 

Specifications, Analysis, and Toxicity. Dicyandiamide is identified quaHtatively by paper chromatography and quantitatively by ultraviolet spectrometry of the chromatogram. More commonly, total nitrogen analysis is used as a purity control or the dicyandiamide is converted by hydrolysis to guanylurea, which is determined gravimetrically as the nickel salt (50). Methods based on the precipitation of silver dicyandiamide picrate are sometimes used (51). Dicyandiamide can also be titrated with tetrabutylammonium hydroxide ia pyridine solution. Table 4 gives a typical analysis of a commercial sample. Dicyandiamide is essentially nontoxic. It may, however, cause dermatitis. 

Hydrazine sulfate is used as a reducing agent in analytical chemistry for gravimetric measurement of nickel, cobalt, and other metals, and in peptide analysis in the separation of polonium from tellurium as an antioxidant in... 

Schiff s bases formed from o-hydroxyaldehydes often form reagents of service in analysis. For example, the base formed with ethylenediamine forms an insoluble complex with nickel (14) which has been used for its gravimetric determination. 2-(o-Hydroxyphenyl)benzoxazole (15a) has been... 

Compound (17-G-V) is used in analysis for the gravimetric determination of nickel. Phosphine complexes of the type tro/is-NiX and (L—L)NiX2 are used as precursors for numerous catalytic reactions some of these have also been discussed as potential anti-tumor agents.2 An unusual class of compounds are the metalladithi-olenes, for example, (17-G-VI) and (17-G-VII), which are readily oxidized to give, formally, Ni111 and Ni1 species. These compounds show metallic conductivity and may show low-temperature superconductivity.3... 

Estimation of Chromium.—In the analysis of chromites or of other substances containing chromium, such as leather ashes, pigments, etc., it is first necessary to obtain a solution. This is done by finely powdering the substance and heating it with a suitable flux in a crucible, preferably of nickel. Many fluxes have been employed, usually caustic alkali or alkali carbonates, but the one in most common use at present is sodium peroxide, whereby the chromium compound is rapidly converted to a chromate. - Excess of alkali is removed by boiling with ammonium carbonate, which also precipitates any iron present. The filtrate is then acidified with dilute sulphuric acid and the chromium estimated either by gravimetric or volumetric methods. 

In these experiments, nickel hydroxide was mixed in a proportion of 12.4% with finely divided silica (Cabosil), pressed in a die and dehydrated at 200°, under vacuum, in the infrared analysis cell. Composition of the sample was therefore different from the composition of the samples used in the gravimetric or calorimetric work [NiO(200°)] and possible effects of the support cannot be, a priori, completely excluded. Calorimetric experiments with the supported samples have shown, however, that their reactivity toward CO is very similar to the reactivity ofNiO(200°). 

Method 1. Polymerization of Bis(thiooxamides) with Metal Salts Dithiooxamide, or rubeanic acid as it is commonly referred to in the literature, has been widely used for the quantitative analysis of metals. In particular, copper, nickel, and cobalt form complexes that can be analyzed gravimetrically... 

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