Question

Use Le Châtelier’s principle to predict what will happen if the temperature of the following equilibrium system is decreased. The reaction in the forward direction is endothermic.
Co(H2O)62+(aq) + 4Cl(aq)  CoCl42(aq) + 6H2O(l)
pink purple/blue

Answer 1

Cooling shifts the equilibrium toward the exothermic (reverse) reaction. Because the forward reaction is endothermic (heat is "consumed"), lowering T favors the reverse, producing more Co(H2O)6^2+ (pink) and less CoCl4^2− (blue/purple). The solution will become more pink.