Molten sodium tetraborate

Figure 9.5. The dependence of the speed of the partially counter-balanced body on its mass when it moves down and up in molten sodium tetraborate at 935°C.

Sodium tetraborate (Spectroflux 200 , Johnson and Matthey Co.) was tried with much greater success. Disks produced by fusion of 0.5000 g of calcined gypsum and 6.00 g of sodium tetraborate (Table 1) produced absolutely clear and transparent disks with perfect surfaces. The use of a higher specimen to flux ratio was dictated by the lower solubility of anhydrite in molten borax. 

The pO drop at the equivalence point corresponds to the ligand number 1, which confirms the running of the interaction (1.2.91) in molten Nal. This interaction is characterized by a pK value of —5.02 0.6. It should be emphasized that with the excess of the Lux acid the equilibrium is achieved slowly enough. This seems to be caused by the fact that sodium tetraborate is practically completely polymerized, although the polymerizations effects on the titration process are less pronounced than in the case of B203. After the equivalence point, with the pO drop of 3-3.5 pO units, the equilibrium conditions are achieved in a shorter period, since under these conditions all the polymerized particles are destroyed. The excess of the base over that necessary for the formation of B02 results in the fixation of O2- by the formed metaborate, which demonstrates the oxoacidic properties. The dependence of the ligand number on the initial titrant molality allows us to assume that the final product is sodium orthoborate, B03- (equation (1.2.92)), whose pK value is close to 2. All that we have said above shows that the oxoacidic properties of tetraborate ions in molten sodium iodide are stronger... 

V.L. Cherginets and V.V. Banik, Potentiometric Investigation of Acidic Properties of Sodium Vanadate and Sodium Tetraborate in Molten Sodium Iodide at 700 °C, Zh. Fiz. Khim. 68 (1994) 145-147. 

We are interested in vanadoborate cluster materials both as precursors to porous solids and as a new class of molecular magnets. We have synthesized a variety of vanadoborate cluster compounds 1-7, primarily by use of two different synthetic routes. The first involves hydrothermal synthesis, using sodium tetraborate ( borax ) as the boron source and the second uses molten boric acid as the reaction medium. In general anionic clusters are found. Herein we report that these have novel electronic and bonding arangements which affect their magnetic behaviour and also that they may be cross-linked together by metal centers such as Cd to form stable microporous phases. 

Inorganic substances that do not dissolve in acid can usually be dissolved by a hot, molten inorganic flux, examples of which are lithium tetraborate ( 26407) and sodium hydroxide (NaOH). Mix the finely powdered unknown with a mass of solid flux that is 2 to 20 times the mass of the unknown. Fuse (melt) the mixture in a platinum-gold alloy crucible at 300° to 1 200°C in a furnace or over a burner. When the sample is homogeneous, carefully pour the molten flux into a beaker containing 10 wt% aqueous HNO to dissolve the product. 

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