Thermodynamic calculation of Sn(IV)-NH4+-Cl-H2O system

According to the principles of simultaneous equilibrium and electronic charge neutrality, the thermodynamics of Sn(IV)-NH4+-Cl--H2O system under normal condition was calculated. Relation between all sorts of complex of Sn4+ and pH was plotted. Based on thermodynamics analysis and calculation, some experiments were done to validate the relation between the total concentration of tin ion and pH in this system. The results suggest that the total concentration of ammonium and pH are the most important factors which determine whether (NH4)(2)SnCl6 or Sn(OH)(4) exists in this system. Results further suggest when contnet of HCl is more than 6 mol/L, Sn4+ in this system will be also precipitated in the form of (NH4)(2)SnCl6. These results lay the solid theory foundation to prepare pure (NH4)(2)SnCl6, a promising substitution for SnCl4 . 5H(2)O to prepare antimony doped tin oxide(ATO) and indium tin oxide(ITO), from the tinny material.