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It is often combined as a solid solution with hydroxylapatite (Ca 5 (PO 4) 3 OH or Ca 10 (PO 4) 6 (OH) 2) in biological matrices. Chlorapatite (Ca 5 (PO 4 ) 3 Cl) is another related structure. [ 5 ] Industrially, the mineral is an important source of both phosphoric and hydrofluoric acids.
The pH is measured in soil-water (1:1) and soil-salt (1:2 ) solutions. For convenience, the pH is initially measured in water and then measured in CaCl 2 {\displaystyle {\ce {CaCl2}}} . With the addition of an equal volume of 0.02 M CaCl 2 {\displaystyle {\ce {CaCl2}}} to the soil suspension that was prepared for the water pH, the final soil ...
Structural and thermodynamic properties of crystal hexagonal calcium apatites, Ca 10 (PO 4) 6 (X) 2 (X= OH, F, Cl, Br), have been investigated using an all-atom Born-Huggins-Mayer potential [41] by a molecular dynamics technique. The accuracy of the model at room temperature and atmospheric pressure was checked against crystal structural data ...
Crystalline Chain carbonate and sulfate minerals: calcite (CaCO 3), dolomite (CaMg(CO 3) 2) and gypsum (CaSO 4 ·2H2O). Amorphous clays: young mixtures of silica (SiO 2-OH) and alumina (Al(OH) 3) which have not had time to form regular crystals. Sesquioxide clays: old, highly leached clays which result in oxides of iron, aluminium and titanium ...
Fluoride is classified as a weak base since it only partially associates in solution, but concentrated fluoride is corrosive and can attack the skin. Fluoride is the simplest fluorine anion . In terms of charge and size, the fluoride ion resembles the hydroxide ion.
Fluorapatite (Ca 5 (PO 4) 3 F) is mined along with other apatites for its phosphate content and is used mostly for production of fertilizers. Most of the Earth's fluorine is bound in this mineral, but because the percentage within the mineral is low (3.5%), the fluorine is discarded as waste. Only in the United States is there significant recovery.
Potassium fluoride is prepared by reacting potassium carbonate with hydrofluoric acid. Evaporation of the solution forms crystals of potassium bifluoride. The bifluoride on heating yields potassium fluoride: K 2 CO 3 + 4 HF → 2 KHF 2 + CO 2 ↑ + H 2 O KHF 2 → KF + HF ↑. Platinum or heat resistant plastic containers are often used for ...
An electrochemical cell may be constructed using such a crystal as a membrane separating two fluoride solutions. This cell acts as a concentration cell with transference where the fluoride transport number is 1. As transference of charge through the crystal is almost exclusively due to fluoride, the electrode is highly specific to fluoride.