Cobalt Complexes Cobalt ions form the complex ion hexaaquacobalt(II), [Co(H20).]2+, with water molecules. In the presence of chloride ions the complex ion tetrachlorocobalt(II) (CoCl4]2-is formed. [Co(H20).]2+ (aq, pink) + 4C1-(aq) = [CoC14]2-(aq, blue) + 6H2O(1) Focus Questions: 1. What is the dominant species of cobalt at each step? 2. Is the formation of the tetrachlorocobalt(II) complex an exothermic or an endothermic process? (Hint: watch for temperature changes). 3. Are there any other ways of shifting this equilibrium?
