Is magnesium chloride stable

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Reactivity of magnesium (II) chloride

Representation of magnesium (melt electrolysis)

The fused-salt electrolysis of anhydrous magnesium chloride takes place at approx. 800 and 5-7 with the addition of potassium chloride and calcium chloride to lower the melting point. Chlorine is produced on the graphite anodes and liquid magnesium collects on the iron cathodes and is separated off.

Reaction with water

Magnesium chloride eagerly absorbs water. It dissolves very quickly in the air and forms a series of stable hydrates. The aqueous solution reacts neutrally (= 10.5), the tendency to protolysis of the [Mg (H2O)6]2+ is consequently less pronounced.

Thermal decomposition of the solution

Due to hydrolytic cleavage, MgCl escapes during evaporation2-Solutions of hydrogen chloride. Therefore, the hexahydrate can only be dehydrated in an HCl atmosphere without decomposition.

Detection of Mg2+ as Mg (NH4) PO4

Magnesium ions form with (NH4)2HPO4 a white precipitate of magnesium ammonium phosphate hexahydrate, which is sparingly soluble in water. Since approx2+, Sr2+, Ba2+ and heavy metal ions also result in precipitation with phosphate, they must be separated off beforehand.

Quantitative determination of Mg2+

Magnesium ions have a high capacity to form complexes with mono- and multidentate ligands. The content of Mg2+ can therefore be determined complexometrically with EDTA (ethylenediaminetetraacetate, complexone III) as a standard solution.

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