Monochloramine

Chloramine is used as a disinfectant for water. It is less aggressive than chlorine and more stable against light than hypochlorites. Some of the unregulated byproducts may possibly pose greater health risks than the regulated chemicals. Due to its acidic nature, adding chloramine to the water supply may increase exposure to lead in drinking water, especially in areas with older housing; this exposure can result in increased lead levels in the bloodstream, which may pose a significant health risk. Fortunately, water treatment plants can add caustic chemicals at the plant which have the dual purpose of reducing the corrosivity of the water, and stabilizing the disinfectant. Swimming pool disinfection In swimming pools, chloramines are formed by the reaction of free chlorine with amine groups present in organic substances, mainly those biological in origin (e.g., urea in sweat and urine). Chloramines, compared to free chlorine, are both less effective as a sanitizer and, if not managed correctly, more irritating to the eyes of swimmers. Chloramines are responsible for the distinctive "chlorine" smell of swimming pools, which is often misattributed to elemental chlorine by the public. Some pool test kits designed for use by homeowners do not distinguish free chlorine and chloramines, which can be misleading and lead to non-optimal levels of chloramines in the pool water. There is also evidence that exposure to chloramine can contribute to respiratory problems, including asthma, among swimmers. Respiratory problems related to chloramine exposure are common and prevalent among competitive swimmers. Though chloramine's distinctive smell has been described by some as pleasant and even nostalgic, its formation in pool water as a result of bodily fluids being exposed to chlorine can be minimised by encouraging showering and other hygiene methods prior to entering the pool, as well as refraining from swimming while suffering from digestive illnesses and taking breaks to use the bathroom, instead of simply urinating in the pool. ==Safety==

US EPA drinking water quality standards limit chloramine concentration for public water systems to 4 parts per million (ppm) based on a running annual average of all samples in the distribution system. In order to meet EPA-regulated limits on halogenated disinfection by-products, many utilities are switching from chlorination to chloramination. While chloramination produces fewer regulated total halogenated disinfection by-products, it can produce greater concentrations of unregulated iodinated disinfection byproducts and N-nitrosodimethylamine. Both iodinated disinfection by-products and N-nitrosodimethylamine have been shown to be genotoxic, causing damage to the genetic information within a cell resulting in mutations which may lead to cancer. Lead poisoning incidents In the year 2000, Washington, DC, switched from chlorine to monochloramine, causing lead to leach from unreplaced pipes. The number of babies with elevated blood lead levels rose about tenfold, and by one estimate fetal deaths rose between 32% and 63%. Trenton, Missouri made the same switch, causing about one quarter of tested households to exceed EPA drinking water lead limits in the period from 2017 to 2019. 20 children tested positive for lead poisoning in 2016 alone. ==Synthesis and chemical reactions==

Chloramine is readily soluble in water, ether, but less so in chloroform, and carbon tetrachloride. When in a gaseious form and an aqueous solution, it is thermally slightly more stable. Production In dilute aqueous solution, chloramine is prepared by the reaction of ammonia with sodium hypochlorite: : RR′NCl + H2O RR′NH + HOCl The quantitative hydrolysis constant (K value) represents the bactericidal power of chloramines, and is generally in the range.10−4 to 10−10 ( for monochloramine). It is given by the formula below: : K = \frac{ c_{\text{RR}'\text{NH}} \cdot c_\text{HOCl} }{ c_{\text{RR}'\text{NCl}} } In aqueous solution, chloramine slowly decomposes to dinitrogen and ammonium chloride in a neutral or mildly alkaline (pH ≤ 11) medium: : 3 NH2Cl → N2 + NH4Cl + 2 HCl However, only a few percent of a 0.1 M chloramine solution in water decomposes according to the formula in several weeks. At pH values above 11, the following reaction with hydroxide ions slowly occurs: : 3 NH2Cl + 3 OH− → NH3 + N2 + 3 Cl− + 3 H2O In an acidic medium at pH values of around 4, chloramine disproportionates to form dichloramine, which in turn disproportionates again at pH values below 3 to form nitrogen trichloride: : 2 NH2Cl + H+ NHCl2 + : 3 NHCl2 + H+ 2 NCl3 + At low pH values, nitrogen trichloride dominates and at pH 3–5 dichloramine dominates. These equilibria are disturbed by the irreversible decomposition of both compounds: : NHCl2 + NCl3 + 2 H2O → N2 + 3 HCl + 2 HOCl Reactions In water, chloramine is pH-neutral. It is an oxidizing agent (acidic solution: , in basic solution ): but only possesses 0.4% of the biocidal effect of HClO. ==See also==