KMgSO4Cl3H2O

KMgSO4Cl3H2O is an inorganic salt comprising potassium, magnesium, sulfate, chloride, and a water of crystallisation. Its molecular formula can be represented as KMg(SO4)Cl3·H2O and it is sometimes referred to as potassium magnesium trichlorosulfate monohydrate. The compound crystallises in a monoclinic lattice and typically appears as a pale yellow to colorless hygroscopic powder. The presence of both sulfate and chloride anions provides this salt with distinctive solubility characteristics: it dissolves readily in water to give a clear, colourless solution, but is less soluble in ethanol or dilute organic solvents. Because of its mixed halide and oxyanion character, it is sometimes employed as a laboratory reagent in the preparation of magnesium or potassium halides.

Preparation routes for KMgSO4Cl3H2O usually involve a double displacement reaction between a soluble chloride salt of potassium or magnesium and a soluble sulfate salt, followed by slow crystallisation in an aqueous medium at ambient temperature. A typical synthetic scheme is the reaction of potassium sulfate with magnesium chloride in the presence of excess chloride, then the subsequent addition of a stoichiometric amount of sulfate to promote the formation of the trichlorosulfate complex and the inclusion of a single water molecule in the crystal lattice. The final product is isolated by filtration, washing with de‑ionised water, and drying under vacuum.

In terms of safety, the compound should be handled with standard laboratory precautions. It is non‑toxic in small quantities, but ingestion or inhalation of dust may cause mild irritation to the skin, eyes or respiratory tract. The salt should be stored in a cool, dry place, protected from light, and disposed of in accordance with local regulations for inorganic salts. Its stability under normal laboratory conditions makes it a convenient material for analytical and preparative applications that require a source of both magnesium and chloride ions.