Lithium (III) To Chromium (II) Using Nitrogen

The aim of this experiment is to reduce chromium (III) to chromium (II) using Zinc as an oxidising reagent using Schlenk techniques in the inert gas atmosphere using Nitrogen. The goal is not to let oxidation happen that will prevent the formation of chromium (II) species. Also, the aim of this experiment is to successfully form chromium (II) acetate, to find its percentage yield and to conduct IR analysis to prove the success of the reaction as well as the purity of the compound. Magnetic susceptibility measurements will be required to determine whether the complex is diamagnetic or paramagnetic.
Introduction:
Chromium is a transition metal found in d-block of the Periodic Table. It was discovered in 1761 and isolated only in 1797 by Louis …show more content…
Discussion and Conclusion:
During the addition of granulated zinc, chromium (III) chloride to HCl solution we observed colour change form dark green to blue. This is due to the fact that reduction reaction is taking place, reducing Cr(III) to Cr(II). Flask containing blue Cr(II) solution was left for 30 minutes in the fume hood while the solution of sodium acetate and water was prepared and degassed. Slight appearance of green colour was observed. This was due to the oxidation of small amounts of Cr(II) to Cr(III). Further colour change from blue to purple/red is due to the substitution of chloride and water ligands to acetate ligands on the chromium