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Physical & Chemical properties

Water solubility

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Description of key information

In an experimental study (see: D_K1WaterSol DPT557/012940 key; Doc. No. 119-001) the overall mean water solubility of the test substance was determined to be 364 g/L (> 28%) at 20°C and pH 1.4 - 1.6 This is carried out through placing an excessive amount of triple salt solution, and the solubility is determined by titration of KHSO5 species in solution. In a different experiment (see: B_K1Watersol 3280-27 key; Doc. No. 119-003) the solubility of the test substance was determined by visual inspection to be 297-357 g/l (25-30 %) at 22 °C. This range was found at the pH values 4, 7 and 9. 
The difference in values represents the solubility of the more soluble single salt KHSO5 and not the solubility of the KMPS triple salt. In water the anions of each constituent of the triple salt have independent solubility. The overall solubility is dependent on the least soluble anion which represents 297-357 g/l while the most soluble anion KHSO5 has a solubility of 364 g/L. Nevertheless, these two experimental results are in good accordance, the 364g/L was choose as the key value for the CSA as this could represent the worst case situation. Solubility increases slightly with decreasing pH.

Key value for chemical safety assessment

Water solubility:
364 000 mg/L
at the temperature of:
20 °C

Additional information