Colorless gas with a sharp odor of ammonia NH3 not only dissolves well in water with the release of heat. The substance actively interacts with H molecules2O with the formation of weak alkali. The solution received several names, one of them - ammonia water. The compound has surprising properties, which are in the way of formation, composition and chemical reactions.
Ammonium ion formation
An ammonium ion with one positivecharge and a special type of weak covalent bond - donor-acceptor. According to its size, charge and some other features, it resembles a potassium cation and behaves like alkali metals. Unusually chemically, the compound reacts with acids, forms salts that are of great practical importance. Names in which the characteristics of the preparation and properties of the substance are reflected:
- ammonia water;
- ammonium hydroxide;
- hydrate of ammonia;
- acrid ammonium.
Care must be taken when working with ammonia and its derivatives. Important to remember:
- Ammonium water has an unpleasant odor. The released gas irritates the mucous surface of the nasal cavity, the eye, causes a cough.
- When ammonia is stored in ammonia in tightly closed bottles, ampoules are emitted ammonia.
- You can detect without appliances, just by smell, even a small amount of gas in the solution and air.
- The ratio between molecules and cations in solution varies at different pH.
- At a value of about 7, the concentration of toxic gas NH3, the amount of NH cations less harmful to living organisms increases4+
Preparation of ammonium hydroxide. Physical properties
When ammonia is dissolved in water, ammonia water is formed. The formula for this substance is NH4OH, but in fact there are simultaneously ions
NH4+, OH-, NH3 and H2O. In the chemical reaction of ion exchange between ammonia and water, an equilibrium state is established. The process can be reflected by means of a scheme in which oppositely directed arrows indicate the reversibility of phenomena.
In the laboratory, the production of ammonia water is carried out inexperiments with nitrogen-containing substances. When mixing ammonia with water, a clear, colorless liquid is obtained. At high pressures, the solubility of the gas increases. Water gives up more ammonia dissolved in it when the temperature rises. For industrial needs and agriculture on an industrial scale, a 25 percent substance is obtained in the dissolution of ammonia. The second method involves using the reaction of coke oven gas with water.
Chemical properties of ammonium hydroxide
When in contact, two liquids - ammonia waterand hydrochloric acid - are covered with clubs of white smoke. It consists of particles of the reaction product - ammonium chloride. With a volatile substance such as hydrochloric acid, the reaction occurs directly in the air.
Weakly alkaline chemical properties of ammonia hydrate:
- The substance reversibly dissociates in water to form an ammonium cation and a hydroxide ion.
- In the presence of an NH4+ a colorless solution of phenolphthalein turns into a crimson color, as in alkalis.
- The chemical reaction of neutralization with acids leads to the formation of ammonium and water salts: NH4OH + HCl = NH4Cl + H2O.
- Ammoniac water enters into ion exchange reactions with metal salts to which weak bases correspond, while a water insoluble hydroxide is formed: 2NH4OH + CuCl2 = 2NH4Cl + Cu (OH)2 (blue precipitate).
Ammonia water: application in different branches of the economy
An unusual substance is widely used in everyday life,agriculture, medicine, industry. Technical ammonia hydrate is used in agriculture, production of soda ash, dyes and other products. In liquid fertilizer, nitrogen is contained in a form easily assimilated by plants. The substance is considered the cheapest and most effective for application in the presowing period for all crops.
The production of ammonia water is expended inthree times less than the release of solid granular nitrogen fertilizers. For the storage and transportation of liquid, hermetically sealed steel tanks are used. Some types of paints and hair bleaching agents are made using caustic ammonium. In each medical institution there are preparations with ammonia alcohol - a 10-percent solution of ammonia.
Ammonium salts: properties and practical significance
Substances that are obtained by interactionammonium hydroxide with acids, are used in economic activities. Salts decompose on heating, dissolve in water, undergo hydrolysis. They enter into chemical reactions with alkalis and other substances. The most important practical importance was acquired by chlorides, nitrates, sulfates, phosphates and ammonium carbonates.
It is very important to follow the rules and measuressafety, by working with substances that contain an ammonium ion. When stored in warehouses of industrial and agricultural enterprises, in subsidiary farms there should be no contact of such compounds with lime and alkalis. If the leaktightness of the packages is broken, a chemical reaction will begin with the release of the toxic gas. Everyone who has to work with ammonia water and its salts must know the basics of chemistry. If the safety requirements are met, the substances used will not harm people and the environment.</ p>