The results of studies the physicochemical properties extraction phosphoric acids containing magnesium in presence ammonium nitrate are presented. A decrease heat vaporization H 3 PO 4 -H 2 O system was found range acid concentrations 20-30% and 37-45% P 5 . At an concentration 20, 35% 45% there is a minimum electrical conductivity, while at 30 40% , conductivity solutions reaches maximum value...