|
|
|
|
Sodium fluoride
|
| |
|
| |
Sodium fluoride is the chemical compound with the formula NaF. This colourless solid is the main source of the fluoride ion in diverse applications. NaF is less expensive and less hygroscopic than potassium fluoride (KF).
ProductionNaF is prepared by neutralizing waste hydrofluoric acid resulting from the production of superphosphate fertilizer. It is also generated by treating sodium hydroxide and sodium carbonate with hydrofluoric acid, followed by concentrating the resulting solutions, sometimes with the addition of alcohols to precipitate the NaF:
- HF + NaOH ? NaF + H2O
From solutions containing HF, sodium fluoride precipitates as the bifluoride salt NaHF2. Heating the latter releases HF and gives NaF.
- HF + NaF NaHF2
In a 1986 report, the annual, worldwide consumption of NaF was estimated to be several million tonnes.
Structure and basic propertiesNaF crystallizes in the sodium chloride motif where both Na+ and F- occupy octahedral coordination sites.
It is an ionic compound, dissolving to give separated Na+ and F- ions.
ApplicationsNaF is used as a cleaning agent, often to remove iron stains.
Discussion
Ask a question about 'Sodium fluoride' Start a new discussion about 'Sodium fluoride' Answer questions from other users |
Recent Posts
Encyclopedia
Sodium fluoride is the chemical compound with the formula NaF. This colourless solid is the main source of the fluoride ion in diverse applications. NaF is less expensive and less hygroscopic than potassium fluoride (KF).
ProductionNaF is prepared by neutralizing waste hydrofluoric acid resulting from the production of superphosphate fertilizer. It is also generated by treating sodium hydroxide and sodium carbonate with hydrofluoric acid, followed by concentrating the resulting solutions, sometimes with the addition of alcohols to precipitate the NaF:
- HF + NaOH ? NaF + H2O
From solutions containing HF, sodium fluoride precipitates as the bifluoride salt NaHF2. Heating the latter releases HF and gives NaF.
- HF + NaF NaHF2
In a 1986 report, the annual, worldwide consumption of NaF was estimated to be several million tonnes.
Structure and basic propertiesNaF crystallizes in the sodium chloride motif where both Na+ and F- occupy octahedral coordination sites.
It is an ionic compound, dissolving to give separated Na+ and F- ions.
ApplicationsNaF is used as a cleaning agent, often to remove iron stains. A variety of specialty chemical applications exist in synthesis and extractive metallurgy. NaF is a reagent for the synthesis of fluorocarbons. Representative substrates include electrophilic chlorides including acyl chlorides, sulfur chlorides, and phosphorus chloride. Like other fluorides, NaF finds use in desilylation in organic synthesis.
Fluoride salts were used widely to enhance the strength of teeth by the formation of fluoroapatite, a naturally occurring component of tooth enamel. In the US, NaF was once used to fluoridate drinking water but its use has been displaced by hexafluorosilicic acid (H2SiF6) or the related sodium salt (Na2SiF6). Toothpaste often contains sodium fluoride to prevent cavities.
SafetyThe lethal dose for a 70 kg human is estimated at 5 – 10 g.
See also
External links- at chemistry.org
- at Scorecard, the pollution information site
|
| |
|
|
