Calcium Iodide: Iodine Dissolved over Amorphous Phosphorus and Neutralised with Milk of Lime (Liebig, Thorpe 1912)

Iodine stirred into hot water over red phosphorus turns into hydriodic acid. Milk of lime turns that acid into calcium iodide, and the phosphorus leaves as an insoluble sludge. Result: a solution of calcium iodide; boiled down, deliquescent needles; fused dry in a closed vessel, the anhydrous salt. Source: Thorpe, Dictionary of Applied Chemistry vol. 1 (1912), p. 604, after Liebig (Annalen 121, 222). Not given: water for the milk of lime. Picture drawn by Youblob.

中级

1 day

说明

Phosphorus under hot water

Cover 1 oz of amorphous (red) phosphorus with 30 oz of hot water.

所需工具：

红磷

水

玻璃烧杯

Stir in the iodine

Add finely powdered iodine little by little, stirring all the time, as long as it dissolves without colour. About 13½ oz dissolves.

此步骤所需材料：

碘13.5 盎司

所需工具：

石制研钵与研杵

Neutralise with milk of lime

Pour the colourless liquid off the small deposit. Make it slightly alkaline with milk of lime; about 8 oz of lime is needed.

此步骤所需材料：

生石灰8 盎司

所需工具：

水

玻璃烧杯

Strain and wash

Strain the solution and wash the residue of calcium phosphate, phosphite and hydroxide. The solution holds the calcium iodide. Ours: strain through muslin.

所需工具：

平纹细布

水

Evaporate, then fuse dry

Evaporate to get the hydrate in deliquescent needles. For the dry salt, evaporate and fuse the residue in a closed vessel; in air it gives off iodine and turns to lime.

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