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The (Na⁺,K⁺)-(Cl^-,SO₄^2-)-H₂O system

In the quaternary (Na⁺,K⁺)-(Cl^-,SO₄^2-)-H₂O system at 100°C, the following solid phases appear:

• NaCl, Sodium chloride
• Na₂SO₄, Sodium sulfate
• KCl, Potassium chloride
• K₂SO₄, Potassium sulfate
• NaK₃(SO₄)₂, Glaserite

Figure 1 shows the concentration ranges in which the various solid phases appear. The concentration unit is charge fraction, which corresponds to equivalent fraction. 

Figure 1. The (Na⁺,K⁺) - (Cl^-,SO₄^2-)-H₂O system at 100°C

Each corner of figure 1 represents a binary solution, and each of the four sides a ternary solution. The lower left corner of figure 1 represents a KCl solution, the lower right corner a K₂SO₄ solution. Correspondingly, the upper corners represent a NaCl and a Na₂SO₄ solution. A contour chart of the same system is shown in figure 2.

Figure 2. The (Na⁺,K⁺) - (Cl^-,SO₄^2-)-H₂O system at 100°C, shown as a contour plot, the contours mark the water content in mass percent.

Finally, the same diagram is shown in figure 3 in three dimensions.

Figure 3. The (Na⁺,K⁺) - (Cl^-,SO₄^2-)-H₂O system at 100°C, shown as a surface plot, the surface mark the water content in mass percent.