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The mysterious world of ammonia: Why can't it be simply isolated as amino hydroxide?
Ammonia, or ammonia solution, is the result of ammonia dissolving in water. This solution is known as the hydrated form of ammonia gas. Although the name of the amino hydroxide implies that its composition is [NH4][OH−], it is actually impossible to isolate NH4OH sample. This is because in an extremely thin solution, the proportion of NH4+ and OH− ions is very small.
The concentration of ammonia can be measured on the Baumé scale, and typically high-strength commercial products contain about 30% ammonia at 15.5°C (59.9°F).
The alkalinity of ammonia in water
In the aqueous phase, ammonia dehydrates a small portion of water molecules, forming ammonium and hydroxide ions according to the following equilibrium reaction:
NH3 + H2O ⇌ NH4+ + OH−. In 1 M ammonia solution, approximately 0.42% of the ammonia is converted to ammonium, resulting in a pH of 11.63. This means that when the concentration reaches a certain level, the ammonia will affect the surrounding environment with its alkalinity.
Characteristics of saturated solutions
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), the density of a saturated solution is 0.88 g/ml, and the proportion of ammonia can be as high as 35.6%. This property allows ammonia to release gas due to temperature changes, which has important implications in industrial applications.
Application fields
Compared with anhydrous ammonia, ammonia has relatively narrow uses and is mainly concentrated in cleaning products.
Cleaning products
Ammonia is widely used in detergents, and its clear properties make it an important ingredient in household cleaning. Ammonia sold on the market is usually sold under the name "ammonia", and there are even products with added fragrance (such as lemon or pine). Experts warn that ammonia should not be used to clean vehicle touch screens because it could damage the screen's anti-glare and anti-fingerprint coating.
Can be used to clean glass, porcelain and stainless steel, and is particularly good at removing grease.
Food production
In food production, ammonia is used in the production of chemical bulking agents, such as fermented ammonia (ammonium carbonate). As an acidity regulator, it effectively reduces acidity in foods and is recognized by the U.S. Food and Drug Administration as Generally Recognized as Safe (GRAS) when used in food-grade versions.
Water treatment
Ammonia's use in water treatment also includes the generation of chloramines, which are superior disinfectants to direct chlorination and remain effective for long periods of time in stagnant water pipes. Additionally, for aquarium setups, ammonia is an integral part of the sterile circulation of fish.
Furniture making
In furniture making, ammonia was also used to darken or stain wood containing tannins, a technique that was widely used during the Craftsman movement to give furniture deep colors.
Laboratory applications
In the laboratory, ammonia is used in traditional qualitative inorganic analysis as a complexing agent and alkaline agent. It is even often seen when cleaning precious metal jewelry.
Challenges and risks of ammonia
Although ammonia has a wide range of applications, its use also comes with certain dangers. Ammonia is irritating to the eyes and mucous membranes, and experts advise caution when using it to avoid mixing it with chlorine-containing products, as this may produce toxic chloramine gas.
As the understanding of ammonia deepens, many people begin to question why such an ancient compound still has such a special position in modern times. Will ammonia be re-evaluated and utilized in more areas in the future?
