| IUPAC name
| Systematic IUPAC name
| Other names
|Molar mass|| 95.211 g/mol (anhydrous)|
203.31 g/mol (hexahydrate)
|Appearance||white or colorless crystalline solid|
|Density|| 2.32 g/cm3 (anhydrous) |
1.569 g/cm3 (hexahydrate)
|Melting point||714 °C (1,317 °F; 987 K) 117 °C (243 °F; 390 K) (hexahydrate)|
| anhydrous |
52.9 g/100 mL (0 °C)
54.3 g/100 mL (20 °C)
72.6 g/100 mL (100 °C)
167 g/100 mL (20 °C)
|Solubility||slightly soluble in acetone, pyridine|
|Solubility in ethanol||7.4 g/100 mL (30 °C)|
|89.88 J/mol K|
Std enthalpy of
|Safety data sheet||ICSC 0764|
|Lethal dose or concentration (LD, LC):|
LD50 (Median dose)
|2800 mg/kg (oral, rat)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Magnesium chloride also known as Nigari is a chemical compounds with the formula MgCl2.
Magnesium chloride will react with calcium hydroxide to give magnesium hydroxide and calcium chloride:
- MgCl2(aq) + Ca(OH)2 → Mg(OH)2(pp) + CaCl2(aq)
Magnesium chloride is a white hygroscopic solid, soluble in water but poorly soluble in organic solvents, such as ethanol.
Magnesium chloride is available as tofu coagulant, more exactly as "Nigari flakes" or "Nigari salt".
Magnesium chloride sometimes occurs naturally as the mineral bischofite.
Magnesium chloride can be prepared by reacting hydrochloric acid with magnesium or magnesium carbonate.
A cheaper way involves the reaction of magnesium sulfate (Epsom salt) with calcium chloride. The resulting calcium sulfate is filtered off and the magnesium chloride solution is gently heated at 100 °C to remove the water. Since a small amount will hydrolyze, injecting dry hydrogen chloride gas will regenerate the magnesium chloride. Magnesium carbonate can also be used instead of Epsom salt, but since it's very poorly soluble, the reaction needs lengthy boiling under reflux (similarly to converting barium sulfate to carbonate).
- Make elemental magnesium (electrolysis of molten MgCl2 at over 714 °C, or of an eutectic mixture of MgCl2, KCl, NaCl at 475 °C)
- Home-made desiccator
Magnesium chloride is deliquescent and its anhydrous form may cause irritations on contact with skin, eyes or mouth.
Because of its hygroscopicity, magnesium chloride must be stored in an air-tight container.
Magnesium chloride can be safely poured down the drain.