The strength of monochloramine, NH2CI, as an oxidizing agent can be linked to its effect on Pb levels in drinking water. In this study, the equilibrium potential was measured as a function of pH from pH 8 to 12 and compared to a theoretical plot of formal potentials derived from the Nemst equation. The measured equilibrium potential was consistently about 300 mV more negative than the calculated potential - NH2CI is a weaker oxidizing agent than predicted. When the measured potentials are plotted on a Pourbaix diagram, it is found that NH2CI can oxidize Pb to PbO2 only above pH 9.5, while the theoretical values indicate that it can do so at a much lower pH. The validity of the values measured in this experiment is supported by the fact that NH2CI has been shown to oxidize Pb to Pb2+, not PbO2, at pH 8 (1). The work is important because it is known that PbO2 acts as a passivating agent on the inside of lead-bearing plumbing materials.
Clark, Brandi, "Unleaded Drinking Water: Equilibrium Potential Measurements for Monochloramine Disinfectant" (2007). Opportunities for Undergraduate Research Experience Program (OURE). 194.