Which cobalt complex is favored when adding deionized water to cobalt II chlorid

Question

Which cobalt complex is favored when adding deionized water to cobalt II chloride and ethanol? The solution is a purple color and when adding the heat it turned blue. When taken off the heat plate it was added to an ice bath and the solution turned pink so which complex was favored during this process? Also how would one rewrite the equation introducing the energy process, the energy process is +50kk/mol. Use Le Chateliers principle and the equation you write to explain the color changes that resulted from the heating and cooling.

Explanation / Answer

CoCl2 + 2H2O ------> [Co(H2O)2]Cl

this is the complex that forms when water is added. The solution is purple when the coordination number 2 and  changes to blue upon heating as the coordinated water molecules leaves off. Placing in ice bath leads to 4 more water molecules to coordinate and the complex appears in pink.

water molecules coordinating to Co is an exothermic reaction. Therefore placing in ice bath leads to increase in coordination number to 6 as the heat has been taken out of the system by ice bath. And heating leads to removal of water molecules as it is an endothermic process.

CoCl2 <-------> [Co(H2O)2]Cl2 <--------> [Co(H2O)6]Cl2

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