Flouride ions

Zirconium is readily attacked by acidic solutions containing fluorides. As Httle as 3 ppm flouride ion in 50% boiling sulfuric acid corrodes zirconium at 1.25 mm/yr. Solutions of ammonium hydrogen fluoride or potassium hydrogen fluoride have been used for pickling and electropolishing zirconium. Commercial pickling is conducted with nitric—hydrofluoric acid mixtures (see Metal surface treatments). 

Elemental composition U 67.62%, F 32.38%. The compound may be identified by its physical properties. Alpha activity may be measured by an alpha counter or an alpha spectrometer (See Uranium). Flouride ion may be mea-... 

As the flouride ions approach, retaining symmetry, two electrons of each octet can be utilized for SF bonding. Initially, all twelve bonding electrons are localized in the six MOs of the F combinations the configuration is [a e ]. 

The reverse process, called remineralization, is the body s natural defense against tooth decay. Acids produced from food remove the OH ions and thereby weaken the enamel layer. Most toothpastes contain a flouride compound such as NaF or Snp2. What is the function of these compounds in preventing tooth decay ... 

The main source of fluoride in ground water is fluoride-bearing rocks such as fluorospar, fluorite, eiyolite, fluorapatite and hydroxylapatite [12]. The flouride content in ground water is a function of several faetors including hydrogeological environment, solubility of fluoride minerals in water, velocity of flowing water, pH, temperature as well as coneentrations of other species such as calcium and bicarbonate ions in water [13,14]. 

The ionization (fcj) and the reverse (A i) rate constants for the 5 1 solvolyses of several 4,4 -disubstituted benzhydryl flourides were determined in several different aqueous and alcoholic solvents. The Nf and if values for fluoride ion in the log ki = s Nf + Ef) equation were found in these solvent mixtures. The Nf decreased significantly and the if values decreased slightly but remained close to 1.0 as the percentage water increased in each solvent. The results suggest that the fluoride reactions have earlier transition states than either the corresponding bromides or chlorides. The data was used to construct quantitative energy profiles for the reactions of the different fluorides in 80% MeCN/20% water. 

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