Sodium fluoride
Cubic
Na, F
- Sodium fluoride
- Fluorol
- A01AA01
- A12CD01
White to greenish solid
Fixed
2.79 g · cm -3
993 ° C
1704 ° C
- Moderately in water ( 42.2 g · l-1 in water at 20 ° C)
- Poorly in ethanol
1.3252
Risk
1 mg · m-3
- 52 mg · kg -1 ( LD50, rat, oral)
- 52 mg · kg -1 ( LD50, mouse, oral)
- 52 mg · kg -1 ( LD50, rabbit, oral)
Template: Infobox chemical / molecular formula search is not possible
Sodium fluoride is a sodium salt of hydrofluoric acid.
Occurrence
Sodium fluoride occurs in nature in the form of the rare mineral Villiaumit.
Production and representation
Neutralization of concentrated hydrofluoric acid with sodium hydroxide
Excess hydrogen fluoride leads to the formation of sodium hydrogen fluoride:
Reaction of hydrofluoric acid with sodium carbonate:
Starting from the sodium salt of sodium fluoride hexafluorosilicic can be obtained by thermal decomposition.
Properties
The colorless sodium fluoride crystallizes in the sodium chloride structure and can " grow " to single crystals. It is transparent to infrared and ultraviolet light. In water, it is only moderately soluble at all temperatures. Heating hardly increases the solubility. Ethanol does not dissolve. In concentrated sulfuric acid it is made to sodium sulfate and hydrogen fluoride. Due partly taking place hydrolysis, the aqueous solution of sodium fluoride is slightly alkaline. Sodium fluoride acts as an insecticide and is toxic.
Sodium fluoride together with sodium chloride, sodium carbonate, and calcium fluoride with a molten eutectic with sodium sulfate with two melting eutectics. Liquid sodium fluoride conducts electrical current, the resistance decreases with increasing temperature.
The standard enthalpy of formation of sodium fluoride is ΔHf0 = -575 kJ / mol.
Responsiveness
Sodium fluoride and sulfuric acid react to form sodium sulfate, and hydrogen fluoride.
The high toxicity of NaF in comparison to other sodium halides (for example sodium chloride) is due to the effect of the fluoride anion as a strong Lewis base. The fluoride binds to all iron-containing enzymes and blocks them thus.
Use
Sodium fluoride is used as a wood preservative and for the preservation of adhesives. In the electrolytic production of aluminum it is used as a flux in metallurgy as a slag addition to molten metal. Other applications:
- Turbidity and flux in glass production
- For the purification of other fluorides by binding of excess hydrogen fluoride
- Fluorinating agent in organic chemistry.
- Single crystals used in analytical instrumentation as filters, lenses and prisms
- In photometry as a masking agent for iron ions
- Fluoridation of drinking water, salt, toothpaste, etc., fluorine tablets
- Purification of uranium hexafluoride from the reprocessing of
- As a phosphatase inhibitor in molecular biology
- With the Zyklotronprodukt fluorine - 18 as a radiopharmaceutical for bone scintigraphy using positron emission tomography ( or in the 1970s by rektilinearem scanners and ultra - Hochenergiekollimator ).
Precautions
Sodium fluoride is toxic. Inhalation of dusts should be avoided. When working with sodium fluoride gloves should be worn. As a lethal amount of 5-10 g for a 70 kg human is considered.