Monochloramine facts for kids
Quick facts for kids Monochloramine |
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| Other names |
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| Identifiers | |
| CAS number | |
| PubChem | |
| EC number | 234-217-9 |
| KEGG | C19359 |
| MeSH | |
| ChEBI | CHEBI:82415 |
| SMILES | NCl |
| Properties | |
| Molecular formula | |
| Molar mass | 0 g mol-1 |
| Appearance | Colorless gas |
| Melting point | |
| Acidity (pKa) | 14 |
| Basicity (pKb) | 15 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Monochloramine, often called chloramine, is a chemical compound with the formula NH2Cl. It is a colorless liquid when very cold, but we usually find it mixed with water. In this form, it is sometimes used to clean and disinfect things.
Contents
Water Treatment Uses
Chloramine is used to treat water, making it safe for us to drink and use. It is not as strong as chlorine and lasts longer in sunlight.
Cleaning Drinking Water
Chloramine is commonly used in small amounts to clean city water pipes. It is becoming more common than using just chlorine. This is because chloramine is less reactive. It does not disappear as quickly as free chlorine.
Chloramine also creates fewer harmful byproducts. These are substances that can form when disinfectants react with other materials in the water. Some of these byproducts, like chloroform, were identified as substances that could be harmful over a long time. In 1979, the United States Environmental Protection Agency (EPA) started setting rules for how much of these substances could be in our drinking water.
Some other byproducts, not yet regulated, might also pose health risks.
Adding chloramine to water can sometimes cause lead to get into the drinking water. This is especially true in older homes with lead pipes. This can lead to higher lead levels in people's blood, which is a serious health concern. Water treatment plants can add other chemicals to help stop this. These chemicals make the water less corrosive and keep the disinfectant stable.
Disinfecting Swimming Pools
In swimming pools, chloramines are formed when chlorine reacts with substances from our bodies, like sweat and sometimes urine. Chloramines are not as good at cleaning pools as free chlorine. They can also irritate swimmers' eyes if not managed well.
Chloramines are actually what cause the strong "chlorine" smell in pools. Many people think this smell comes from chlorine itself, but it is usually from chloramines. Some home pool test kits do not tell the difference between free chlorine and chloramines. This can lead to too many chloramines in the pool water.
There is also evidence that breathing in chloramines can cause breathing problems, like asthma, for swimmers. These problems are common among competitive swimmers.
Even though some people find the "chlorine" smell pleasant, we can reduce chloramine formation. Swimmers should shower before entering the pool. They should also avoid swimming when sick and use the bathroom instead of urinating in the pool.
Safety Information
The US EPA sets limits for chloramine in public water systems. The concentration should not be more than 4 parts per million (ppm). Many water companies are switching to chloramine from chlorine to meet rules about disinfection by-products.
While chloramine creates fewer regulated by-products, it can create more of other substances. These include iodinated disinfection byproducts and N-nitrosodimethylamine. Both of these have been shown to damage cells and potentially lead to serious health issues, including cancer.
Another newly found byproduct is chloronitramide anions. Scientists are still studying how toxic these might be.
Past Lead Poisoning Incidents
In 2000, Washington, DC, changed from chlorine to monochloramine for water treatment. This caused lead to leak from old pipes that had not been replaced. The number of babies with high lead levels in their blood increased significantly. There was also a significant increase in serious health problems for unborn babies.
Trenton, Missouri, made the same change. From 2017 to 2019, about a quarter of homes tested there had lead levels above EPA limits. In 2016 alone, 20 children tested positive for lead poisoning.
In 2023, Professor Marc Edwards from Virginia Tech said that lead spikes happen in several water system changes each year. This is often due to a lack of training and because old lead pipes are still in use. Water companies sometimes do not even know they have lead pipes. The EPA required all US water companies to create a full list of their lead pipes by October 16, 2024.
Making and Breaking Down Chloramine
Chloramine dissolves easily in water. It is very unstable when concentrated. Pure chloramine can break down violently if it gets too warm. It is a bit more stable when it is a gas or mixed in water.
How it is Produced
In a weak water solution, chloramine is made by mixing ammonia with sodium hypochlorite:
- NH3 + NaOCl → NH2Cl + NaOH
Gaseous chloramine can be made by reacting ammonia gas with chlorine gas:
- 2 NH3 + Cl2
NH2Cl + NH4Cl
How it Decomposes
In water, chloramine slowly breaks down. This happens in neutral or slightly alkaline water:
- 3 NH2Cl → N2 + NH4Cl + 2 HCl
However, only a small amount of chloramine in water breaks down this way over several weeks. In acidic water, chloramine can change into other forms, like dichloramine and then nitrogen trichloride. These changes depend on how acidic the water is.
See also
- Disinfection
- Disinfection by-products
- Water treatment
- Pathogen
- Chloramines
