Complex Compounds of Aluminium

Like trivalent 3d transition metal ions, Ap readily forms the oxalato-complex where the two oxygens of the ligand are coordinated to the metal. The complex can be readily prepared by reacting potassium aluminate (formed by dissolving the metal in KOH) with oxalic acid. Adding ethanol leads to the precipitation of the complex. 

The percentage oxalate can be readily determined by titration against permanganate afler heating with sulphuric acid. 

Weigh out accurately about 0.2 g of your preparation into a weighed Pyrex container. Place in an oven at 105°C and heat to constant weight. Calculate the % water of crystallisation. 

Weigh out accurately about 0.2 g of your preparation into a 200 cm beaker, add 50 cm dilute sulphuric acid. Heat to boiling and titrate with standardised 0.02 M permanganate solution to the first very faint pink end point. At the end point, the temperature should be about 80 C. Repeat and calculate from the average result the % oxalate and hence the % purity of your preparation. 

The solution in sulphuric acid, after appropriate dilution, can be used to determine the % K and % Al by atomic absorption. 

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This is a complex compound of aluminium and sodium silicate and sodium sulphide. The typical and most common ultramarine is blue ultramarine, which forms a very fine powder (microscopically crystalline) of a pure blue, reddish blue or greenish blue colour according to the proportions of the components and the method of preparation ultramarines of other tints, especially green and violet ultramarines, are also made. Ultra-marine may be adulterated with gypsum, chalk, clay, heavy spar, zinc white and magnesium carbonate and may also be mixed with glycerine and glucose. 

The research of adsorption properties has shown, that adsorption isotherms of benzene for dealuminated (NH4)2SiF6 zeolite lay below adsorption isotherms of benzene for NaY obtained even at more high adsorption temperatures. In a fig. 1 are shown adsorption isotherms for a sample 2. It is characteristic that at different temperatures (180, 200, 230 C) isotherms are not divided. Apparently, it is connected that so a little benzene is kept on a surface, that the distinction in adsorption at given temperature interval is not fixed. Probably, the samples contain impurities of complex compounds of aluminium with fluorine, that is agreed XRD data. Also relative concentration of defect sites of structure is increased during dealumination, that also can affect on adsorption property. 

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