Solid nickel carbonates

Consider the equilibrium between solid nickel, carbon monoxide, and nickel tetracarbonyl ... 

When nickel nitrate and sodium carbonate solutions are combined, solid nickel carbonate precipitates, leaving a solution of sodium nitrate. Write the conventional equation, total ionic equation, and net ionic equation for this reaction. 

The net ionic equation tells us that nickel ions from one solution combine with the carbonate ions from the other solution to form solid nickel carbonate. The sodium ions and nitrate ions that were in the separate solutions remain as ions in the combined solution. 

The successful conversion of graphite to diamond involves crystallizing the diamond from a liquid melt. The solvent most often used is nickel metal, or alloys of nickel with other ferrous metals. The reason for this success can be seen by referring to Figure 15.7, the binary (solid + liquid) phase diagram for (nickel + carbon).u8 We note from the figure that (Ni + C) forms a simple... 

OtherTitanates. Nickel titanate [12033-39-1]y NiTi03, is a canary-yellow solid having a density of 73(00). When a mixture of antimony oxide, nickel carbonate, and titanium dioxide is heated at 980°C, nickel antimony titanate [8007-18-9] forms, which is used as a yellow pigment (95). 

A solution of 295 g. (1.79 moles) of m-nitroacetophenone [Org. Syntheses Coll. Vol. 2, 434 (1943)] in 1.1 1. of absolute ethanol is shaken with 1.5 tablespoons of Raney nickel catalyst [Org. Syntheses, 21, 15 (1940)] at 50° under an initial hydrogen pressure of 1950 lb. After uptake of hydrogen has ceased, the solvent is evaporated and the residue triturated with 400 ml. of a mixture of cold water and excess concentrated hydrochloric acid. The undissolved portion after filtration is treated again with hydrochloric acid. The combined insoluble portions from four reduction batches are washed with water until free from acid and dried (170 g.) and subjected to reduction as before. The combined hydrochloric acid solutions are treated with solid sodium carbonate with stirring until the solution is alkaline, and the precipitated m-aminoacetophenone is removed by filtration. 

Nucleation appears to occur readily in most carbonate dissociations. Product recrystallization may occur only after COj release as shown for CaCO, [3,4] and basic nickel carbonate [71]. There is little evidence for promotion of the interface reaction by the solid product, instead the solid product is an inhibitor through increasing the contribution of the reverese (recombination) process. Measured values of are usually comparable with reaction enthalpies (Table 12.1.). Together these features suggest that the rates of most carbonate dissociations are controlled by anion breakdown at the boundaries of reactant particles. 

Consider the neutralization reaction that takes place when hydrochloric acid reacts with solid nickel(II) carbonate. 

The electrolyte in this fuel cell is concentrated (85 wt.%) potassium hydroxide in fuel cells operated at high temperature ( 250°C) or less concentrated (35-50 wt.%) potassium hydroxide for lower temperature (<120°C) operation. The electrolyte is retained in a matrix (usually asbestos) and a wide range of electrocatalysts can be used, for example, nickel, silver, metal oxides, spinels, and noble metals. The fuel supply is limited to nonreactive constituents except for hydrogen. Carbon monoxide is a poison and the produced carbon dioxide (in the case of having carbon monoxide) will react with the potassium hydroxide to form solid potassium carbonate, thus altering the electrolyte. Even the small amount of carbon dioxide in air must be considered as a problem in the alkaline cell. 

Other reactions important to reforming are also considered in the reaction network in Figure 10, include the water-gas-shift reaction and its reverse, the reversible adsorption and decomposition of water, the desorption and adsorption of reforming products like CO, CO2, and H2, and the formation of hydrocarbons like CH. The formation of dissolved carbon, oxygen, and hydrogen in bulk nickel is also considered. Dissolved C, 0, or H may be important in the transport of those elements to or from interfaces with other solid phase (carbon, carbides, oxides, support). The possible formation of NiO from H2O is also shown. Finally, an important reaction to consider is the formation of a deactivating layer of carbons (6 or e carbon states). 

Smurov precipitated nickel carbonate by mixing aqueous sodium carbonate and nickel chloride solutions. The solid phase obtained was washed free of chloride and used for the solubility study, but no attempt was made to characterise its stoichiometry and/or its crystal structure. The precipitate was equilibrated with water in a temperature range between 278.15 and 353.15 K. For each temperature the partial pressure of carbon dioxide was varied from 0.0005 atm to = 1 atm. Smurov s data have been ex-... 

Figure A-1 Solubility of precipitated nickel carbonate. Experimental data [38SMU] solid curve experimental data fitted to logn, + BIT + C lnF dotted curve ...

The X-ray diffraction patterns of hydrothermally synthesised anhydrous nickel carbonate were taken, indexed and the constants of the unit cell ascertained. The T, p phase diagram of NiC03(cr) was determined semi-quantitatively. Solid solution formation between NiCOs and MgCOs was established. In addition hellyerite, NiC03-5.5H20, and zaratite were investigated. The latter turned out not to be a single mineral, but a composite of amorphous and fibrous components. 

The stability constants of nickel carbonate complexes were investigated by measuring the solid/liquid distribution ratio of Ni in the absence and presence of varying carbonate concentrations. For this purpose a Ni tracer method was employed. A considerable part of the uncertainty (log, K°, for the reaction Ni " + CO3 NiC03(aq), is calculated to be (4.2 0.4)) inherent in this method arises from the poorly known formation constants of neutral and anionic hydroxo complexes of nickel. 

Potassium hexaazidonickelate(II), K4[Ni(N3)e] , is a yellow-green solid which dissolves to some degree in water and is insoluble in alcohol. The salt deflagrates in a flame test but is not sensitive to mechanical shock [161]. It was obtained by mixing solutions of nickel azide and a tenfold excess potassium azide. A solution of nickel azide was first made by dissolving basic nickel carbonate in hydrazoic acid. The green solution, which was 0.2 M with respect to Ni, was then poured into the potassium azide solution (concentration, 25 g KN3 in 100 ml water). Within a week the complex salt separated as a mass of fine crystals that were washed with ice-cold water and alcohol [161]. 

Either Ni(OH)s or precipitated nickel carbonate is dissolved in hydriodic acid and the solution evaporated to dryness. The solid is recrystallized from alcohol and dried at 140°C. A final sublimation in high vacuum at 500-600°C is recommended. 

Pet] Petrova, E.F., Shvartsmann, L.A., On the Thermodynamies of the Fe-Ni Solid Solutions (in Russian), Dokl. Akad. NaukSSSR, 146(3), 646-648 (1962) (Calculations, Thermodyn., 5) [1963Hec] Heckler, A.J., Winchell, P.G., The Activity of Carbon in Iron-Nickel-Carbon Austenite , Trans. Metall. Soc. AIMS, 227, 13i2-136 (1963) (Experimental, Phase Relations, Thermodyn., 3)... 

In the Mond process for the purification of nickel, carbon monoxide is reacted with heated nickel to produce Ni(CO)4, which is a gas and can therefore be separated from solid impurities ... 

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