Determination of outer sphere and total Chloride content, and formula of unknown Co complex by ion exchange chromatography and Fajan’s method

The objective of this lab is to determine the formula of an unknown Co (III) complex through determination of outer sphere chloride content and hence total chloride content in the complex. Co (III) tends to form numerous coordination complexes, of which the most common ones are those with ammine ligands. The unknown Co(III) complex will have a general formula of [Co(NH3)(6-x)Clx]Cl(3-x) where x is an integer that could have values of 0, 1, 2, or 3.1 The coordination number of Co(III) is 6 so a total of 6 ligands can bind to it. The unknown complex given is a solid and bears two different types of chloride ions-inner sphere chloride ions and outer sphere chloride ions. The inner sphere chloride ions act as ligands while the outer sphere chloride ions act as counter-ions to balance the positive charge of the unknown Co (III) complex. The experimental techniques employed to determine the outer sphere and total chloride content are ion exchange chromatography and fajan's method of chloride ion titration respectively.