Chromium (III) chloride

there is no element with the symbol R, so perhaps it is meant to read CrCl6 which is Chromium Chloride. Hope this helps! for more info on Chromium Chloride visit http://en.wikipedia.org/wiki/Chromium(III)_chloride

Chromium (II) chloride = CrCl2Chromium (III) chloride = CrCl3

Chromium (IV) chloride = CrCl4

Another chemical name is chromium trichloride or chromic chloride. Chromium(III) chloride is a chemical name as well.

The formula of chromium chloride is CrCl3 and the formula for silver chloride is AgCl. The relevant formula unit masses are 158.36 for chromium (III) chloride and 143.32 for silver chloride. The gram atomic masses of chlorine, chromium, and silver are 35.453, 51.996, and 107.866 respectively. Therefore, the mass fraction of chloride in chromium (III) chloride is [3(35.453)/158.36] or 0.671628 and the mass fraction of chloride in silver chloride is 35.453/143.32 or 0.24737. Therefore, to form 75.0 g of silver chloride, (0.24737)(75.0) or 18.55 g of chloride is needed, and this amount of chloride is contained in 18.55/0.6716 or 27.6 g of chromium (III) chloride, to the justified number of significant digits.