The formation of the complex ion Cu NH3 4^2+ from Cu2+ and NH3 is influenced by the pH of the solution. The reaction can be represented by the following chemical equation:Cu2+ + 4NH3 Cu NH3 4^2+To understand the effect of pH on this reaction, we need to consider the behavior of ammonia NH3 in water. Ammonia is a weak base and can react with water to form the ammonium ion NH4+ and hydroxide ion OH- :NH3 + H2O NH4+ + OH-As the pH of a solution is a measure of the concentration of hydrogen ions H+ , a change in pH will affect the concentration of NH3 and NH4+ in the solution. At low pH acidic conditions , there is a high concentration of H+ ions in the solution. These H+ ions will react with the NH3, forming NH4+:NH3 + H+ NH4+This reaction decreases the concentration of free NH3 available to form the complex ion Cu NH3 4^2+. As a result, the formation of the complex ion is less favorable under acidic conditions.At high pH alkaline conditions , there is a low concentration of H+ ions and a high concentration of OH- ions in the solution. This favors the formation of NH3 from NH4+:NH4+ + OH- NH3 + H2OWith a higher concentration of free NH3 available, the formation of the complex ion Cu NH3 4^2+ is more favorable under alkaline conditions.In summary, the formation of the complex ion Cu NH3 4^2+ from Cu2+ and NH3 is more favorable under alkaline conditions high pH due to the increased concentration of free NH3 in the solution. Under acidic conditions low pH , the reaction is less favorable as the concentration of free NH3 is reduced due to the formation of NH4+.