Language
Country/Area
No result found
The strange changes of ammonia: Why does it release toxic chloramine gas in water?
Ammonia, also known as aqueous ammonia solution, ammonia hydroxyl or liquid ammonia, is a solution of ammonia and water with the molecular formula NH3(aq). Although the name "aminohydroxy" implies a salt (NH4OH), it is actually impossible to isolate a sample of aminohydroxy. In extremely dilute solutions, the proportion of NH4+ and OH− ions is extremely small. The concentration of ammonia is usually measured in Baumé degrees, and a 30% ammonia solution in commercial products is approximately equivalent to 26 Baumé degrees.
Basic properties of ammonia in water
In aqueous solution, ammonia deprotonates a small portion of water to form ammonia and hydroxide. The equilibrium reaction of this process can be expressed by the following formula:
NH3 + H2O ⇌ NH4+ + OH−. In 1 M ammonia water, about 0.42% of the ammonia is converted to ammonium ions, which means its pH is about 11.63.
The basic properties of ammonia make it important in a variety of applications, but it also has potential hazards.
Characteristics of saturated solution
Like other gases, the solubility of ammonia in a solvent decreases as the temperature of the solvent increases. At 15.6°C (60.1°F), a saturated solution of ammonia has a density of 0.88 g/ml and contains 35.6% ammonia; as the temperature increases, the molar concentration of the saturated solution decreases and the density increases. When saturated solutions are heated, ammonia gas is released, which requires special safety precautions at elevated temperatures.
Application Areas
Unlike anhydrous ammonia, aqueous ammonia has relatively limited applications on screens outside of cleaning agents. It is primarily used in household and industrial cleaning products. Ammonia is widely used to clean surfaces such as glass, porcelain and stainless steel.
Cleaning Products
Ammonia's cleaning properties make it a common component of household cleaners. Such products may be sold pure or mixed with other ingredients. During the ammonia cleaning process, as the water evaporates, the ammonia also evaporates, which can keep the surface clean and streak-free.
Experts warn that cleaners containing ammonia should not be mixed with any products containing chlorine to avoid the creation of toxic chloramine gas.
Water treatment and food production
In water treatment, ammonia is used to generate chloramines, which act as disinfectants and remain active longer in drinking water than direct chlorination. Ammonia is also used in food production as an acidity regulator and historically as a leavening agent for biscuits.
Laboratory Use
In the laboratory, ammonia is used as a traditional qualitative analytical reagent and is often used to dissolve silver oxide residues and may also be used to clean precious metal jewelry. However, be aware of the possible negative effects on certain gemstones.
The Dangers of Chloramines
Chloramines are gases formed by the reaction of ammonia and chlorine, and their toxicity means that ammonia must be used with extreme caution. Mixing ammonia with chlorine-containing products can release chloramine gas, which can cause respiratory problems and even be life-threatening. Therefore, when using ammonia products, it is very important to avoid contact with any chlorine-containing cleaners.
Although ammonia has many applications in daily life, its potential dangers cannot be ignored. Is this a new challenge brought about by scientific and technological progress, or is it a revelation that people should have a deeper understanding of chemical substances?
