Question

The lodine Clock - Reaction Kinetics DATE: NAME: INSTRUCTOR: SECTION: Show all work for full credit. 1. The complex ion Co(HO), 2 (aq) is pink when placed in solution. Addition of chloride ions creates CoCl, in the solution which is blue in color. a. Write the balanced reaction for the equilibrium. If CoCl, solubility is endothermic, predict what will happen to the solution color if the solution is heated. Co(H₂O)+2 b. What will happen if the solution is cooled?

Answer 1

a) CoCl4 solubility is endothermic, means forward reaction is endothermic. In an endothermic reaction when heat is provided to the reaction, the equilibrium shifts towards the products side i.e in forward direction. So if we heat the solution here, means we are providing heat to the reaction, so the reaction will favour formation of product i.e CoCl4 more. Hence the the solution will turn blue on heating.

a) Bolonced Equation : Co (460 a + (aq) + 40 (aq) Pink Colly (aq) + 640 Blue (tebrachlorocobett (1) cortplec ion) (hexa aqua cobalt II) complex ion)

b) when the solution is cooled, means we are removing heat from the reaction and in an endothermic reaction when heat is removed, equilibrium will shift towards reactants side i.e backward direction. So this reaction will favour formation of hexaaquacobalt complex i.e solution will turn pink.