Ammonium bifluoride is a toxic industrial inorganic compound used in the glass, oil and metallurgical industries. The substance is often used as a substitute for hydrofluoric acid or hydrogen fluoride.
General description and physical properties
Ammonium bifluoride most often has a solid state of aggregation and is presented in the form of crystals. The latter are characterized by high solubility in water, but zero - in acetone and alcohol. Crystals have an orthorhombic syngony with a discrete group of motions Р man. The substance decomposes at temperatures above 238 °C.
This bifluoride has no flammable and explosive properties.
Structure and chemical formula
The substance has several synonymous names, such as ammonium fluoride bifluoride, ammonium fluoride, ammonium hydrofluoride, etc. This compound has the chemical formula NH4(HF 2).
The chemical composition of the substance includes:
- cationammonium (NH4+);
- bifluoride or hydrogen difluoride;
- anion (HF2-).
A notable feature of this compound is the presence of the strongest hydrogen bond with a length of 114 microns. It combines fluorine and hydrogen in a centrosymmetric triatomic bifluoride anion. The energy of this bond exceeds 155 kJ/mol-1.
In the crystalline form of the substance, each ammonium cation is surrounded by four fluoride centers, forming a tetrahedron.
Form of production
Ammonium bifluoride is produced in two forms:
- solid (white crystals);
- as a solution.
Solution is a clear liquid with an odor. The concentration of the starting substance in such a mixture is from 28 to 30%.
Use of substance
Ammonium bifluoride has a very wide range of applications. Specifically, it is used for:
- glass processing;
- Aluminum anodizing;
- as a substitute for the more toxic and corrosive hydrofluoric acid, which improves environmental friendliness and reduces glass processing costs;
- cleaning metal surfaces;
- disinfection of heat pipelines, leather and wood products;
- cast manganese (as a flux);
- removing sand from oil wells;
- rust removal in boilers and pipes;
- cleaning oil lines.
Replacing hydrofluoric acid with ammonium hydrofluoride is used not only inglass processing, but also in well drilling.
Toxicity profile
Hazard class of ammonium bifluoride - ADR 8. This is a rather toxic substance for the human body with a strong corrosive effect. This compound causes irritation on contact with the skin and burns on prolonged exposure. Contact with ammonium bifluoride in the eyes can cause damage to the visual organ.
Inhalation of oxygen in combination with this substance causes the following symptoms:
- irritation of the mucous membranes of the nasopharynx and respiratory tract;
- nosebleeds;
- cough;
- wheezing;
- shortness of breath;
- nausea and vomiting.
Interaction of ammonium bifluoride with water leads to the formation of very dangerous hydrofluoric acid, which enhances the traumatic effect of this compound when it comes into contact with wet skin. In the case of prolonged and intense exposure to the substance on the body, its effect leads to fluoride poisoning, stomach pain, weakness, convulsions and even death.
Regular human contact with ammonium bifluoride leads to the development of a pathological condition called fluorosis, in which fluoride is deposited in bones and teeth.
Sustainable
For the environment, this substance is less dangerous than for humans through direct contact. Ammonium bifluoride has a very important environmental quality - rapid decomposition (within a few days), which eliminates the possibility of its accumulation.
However, in a humid environment, this substance breaks down intohydrofluoric acid and ammonia, which are toxic to living organisms.
