Quantitative Chemical Analysis Harris | Lucy presented by Macmillan Learning Li,,Coo, is an anode for lithium batteries. Cobalt is present as a mixture of Co(III) and Co(II). Most preparations also contain inert lithium salts and moisture. To find the stoichiometry, Co was measured by atomic absorption and its average oxidation state was measured by a potentiometric titration. For the titration, 25.00 mg of solid were dissolved under N in 5.000 ml. containing 0.1000 M Fe+ in 6 M HSO, plus 6 MH, PO, to give a clear pink solution: Co+ + Fe+ Co+ + Fe+ Unreacted Fe+ required 3.048 mL of 0.01687 M K, Cr,O, for complete titration. How many mmol of Co+ are contained in 25.00 mg of the material? mmol of Co+ = mmol Atomic absorption found 56.4 wt% Co in the solid. What is the average oxidation state of Co? average oxidation state of Co: Find y in the formula Li,,,COO,. y = What is the theoretical quotient wt% Li/wt% Co in the solid? wt% Li wt% Co = What is the theoretical quotient wt% Li/wt% Co in the solid? wt% Li wt% Co The observed quotient, after washing away inert lithium salts, was 0.1388 +0.0006. Is the observed quotient consistent with the average cobalt oxidation state? yes no 43. S. Scaccia and M. Carewska, "Determination of Stoichiometry of Li,.,CoO, Materials by Flame Atomic Absorption Spectrometry and Automated Potentiometric Titration," Anal. Chim. Acta 2002, 453, 35