Study of the Polythermal Solubility of the Calcium Chlorate– Ureacarbamide–monoethanolammonium–water System

Abstract In this study, the polythermal solubility of calcium chlorate–urea monoethanolammonium–water systems was systematically investigated. The binary system Ca(ClO₃)₂–H₂O was examined over the temperature range from − 49.0°C to the melting points of the pure components, and its phase diagram was constructed. Three eutectic points were identified, with corresponding liquid-phase compositions and crystallizing solid phases determined for each. The ternary system Ca(ClO₃)₂–[C₃H₈N₂O₃·NH₂CH₂CH₂OH]–H₂O was analyzed within − 47.0°C to − 6.8°C using seven internal sections in conjunction with the binary subsystems, enabling the construction of a detailed polythermal solubility diagram. Distinct crystallization domains were established for ice, calcium chlorate, calcium chlorate dihydrate, tetrahydrate, hexahydrate, and urea monoethanolammonium. The diagram revealed four ternary invariant points, with both liquid-phase compositions and solid-phase constituents determined. The Ca(ClO₃)₂–[C₃H₈N₂O₃·NH₂CH₂CH₂OH]–H₂O system was classified as a simple eutectic type, with no evidence of new compound formation between the initial components. Verification of the phase diagram through reciprocal projections confirmed its accuracy. These findings expand understanding of chloride–urea derivative systems and suggest potential applications in the design of desiccants and physiologically active agents.