Potassium chromium sulfate, KCr(SO4)212H2O, or chromium alum(1), forms violett octaeders and is highly soluble in water.
Potassium chromium sulfate has been used in the leather industry for tanning the hides (nowadays it is replaced by basic chromium sulfate, Cr(OH)SO4). The tanning process stabilizes the leather by cross linking the collagen fibers of the hide. The -COOH groups of the collagen are linked by chromium groups to form -COO-Cr(H2O)4-OOC- bridges enhancing temperature stability (1 m2 of cow leather contains typically about 16 g chromium).
Contributors and Attributions
- Hans Lohninger (Epina eBook Team)