Produced review scientific and technical reference books on individual substances and the two-component systems forming part of the water-salt system K2HPO4 – (NH2)2CO – H2O. To predict phase equilibria in a real system, a mathematical model is proposed that allows one to determine the dependence of the activity coefficient of a substance or ion on the concentration and temperature of the solution. The solution of the system of equations was carried out in the environment of the table processor Microsoft Excel as a result, in terms of potassium hydrogen phosphate, the following characteristics of the eutectic alloy with the calculated content of components in the eutectic were obtained: 36.5 % wt. K2HPO4, 11.5 % wt. (NH2)2CO, 52.0 % wt. H2O, melting point 250.6 K (-22.6 C). In order to search for a composition with a minimum crystallization temperature in the ternary urea – potassium hydrogen phosphate – water system, the simplex K2 HPO46H2O – (NH2)2 was studied CO – H2O by visual polythermal method. The eutectic in the studied system crystallizes at a temperature of minus 28 С and contains 8 % wt. carbamide, 35 % wt. potassium hydrogen phosphate, 57 % wt. water. An analysis of the data obtained by experimental and computational methods showed satisfactory convergence. The average deviation of the calculated data from the experimental ones was 18.9% in composition and 2.3% in terms of the eutectic melting point. The proposed calculation algorithm can be used to predict the characteristics of eutectics in ternary water - salt systems for planning the experiment.
Prediction of phase equilibria in multicomponent water-salt systems by means of translation method
