Calcium chloride is an ionic halide. The anhydrous salt is used as a desiccant. During this process it absorbs so much water that it dissolves in its own crystal lattice water. Because of its hygroscopic nature, the anhydrous form must be kept in tightly-sealed containers. 1M Calcium chloride solution is extensively used in molecular biology. This solution is a sterile-filtered, premixed solution.
1M Calcium chloride solution is mainly used in molecular biology for preparation and transformation of E. coli competent cells as it increases the permeability of cell membrane and as a result plasmid DNA can readily enter the cell.