Romix Posted December 8, 2014 Share Posted December 8, 2014 What happening to aluminium oxide in molten cryolite (Na3AlF6) at 1000°C ? Link to comment Share on other sites More sharing options...
John Cuthber Posted December 8, 2014 Share Posted December 8, 2014 At that temperature aluminium oxide will dissolve in cryolite. If you pass an electric current through the solution you will get aluminium metal and oxygen (which will probably attack the electrode). Link to comment Share on other sites More sharing options...
Romix Posted December 9, 2014 Author Share Posted December 9, 2014 (edited) At that temperature aluminium oxide will dissolve in cryolite. If you pass an electric current through the solution you will get aluminium metal and oxygen (which will probably attack the electrode). Yes agree, if electrodes were made of carbon, platinum electrodes will be fine. What actually happens to the molecules when cryolite used as solvent to dissolve aluminium oxide? For H2O and NaCl google gave me this picture. Not shore if its right. Here is anion and cation of NaCl in solution of H2O. Still don't get it, why dissolution happening? Why some salts are insoluble. Is it something to do with their electron configuration? Alright lets start from simple insoluble ionic metal salts. Barium Sulphate Lead Chloride and Sulphate Silver Chloride That's the electron configuration of metals. Silver Barium Lead Anion: SO4 with a -2 charge and Cl with a -1 charge. Silver transfers one electron to chlorine atom. Usually it happening in displacement reaction, but can be done directly with addition of H2O2. Ok no electrons left in its 5th outer shell, and chlorine filled its shells. Strong ionic bond. Same situation I see in bonding Sodium with Chlorine. But salt produced is soluble. Maybe because Sodium is Alkali Metal, and its electrons really close to the nucleus? Barium Sulphate another insoluble salt. Barium have 2 electrons in its outer shell. [ba+2][sO4-2] All its shells filled. This time anion not just atom, its a molecule. Lead Chloride & Sulphate are both insoluble. 4 electrons in its outer shell... Why this salts are insoluble? Edited December 9, 2014 by Romix Link to comment Share on other sites More sharing options...
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