Changing the pH of a solution can affect the formation of a complex ion by altering the concentrations of the reactants and products involved in the reaction. In the case of [Cu H2O 6]2+ forming [Cu NH3 4 H2O 2]2+, the reaction can be represented as follows:[Cu H2O 6]2+ + 4NH3 [Cu NH3 4 H2O 2]2+ + 4H2OAccording to Le Chatelier's principle, if a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the system will adjust itself to counteract the change and restore a new equilibrium.When the pH of the solution is changed, the concentration of NH3 ammonia in the solution is affected. At low pH values acidic conditions , the concentration of H+ ions is high, which leads to the formation of NH4+ ions through the reaction:NH3 + H+ NH4+This reaction reduces the concentration of NH3 available for the formation of the complex ion [Cu NH3 4 H2O 2]2+. According to Le Chatelier's principle, the equilibrium will shift to the left, favoring the formation of [Cu H2O 6]2+ and reducing the formation of [Cu NH3 4 H2O 2]2+.On the other hand, at high pH values basic conditions , the concentration of OH- ions is high, which reacts with H+ ions to form water:OH- + H+ H2OThis reaction reduces the concentration of H+ ions, leading to a decrease in the formation of NH4+ ions and an increase in the concentration of NH3. As a result, the equilibrium will shift to the right, favoring the formation of [Cu NH3 4 H2O 2]2+ and reducing the formation of [Cu H2O 6]2+.In summary, changing the pH of a solution affects the formation of a complex ion by altering the concentrations of reactants and products involved in the reaction. In the case of [Cu H2O 6]2+ forming [Cu NH3 4 H2O 2]2+, acidic conditions favor the formation of [Cu H2O 6]2+, while basic conditions favor the formation of [Cu NH3 4 H2O 2]2+. This behavior can be explained using Le Chatelier's principle.