title: Effects of pH and calcium on hydrolysis of Na2SiF6 and Na2SnF6. A quasi-constant composition titration study.
abstract: In the present work, hydrolysis reactions of sodium hexafluorosilicate (Na2SiF6) and sodium hexafluorostannate (Na2SnF6) were studied at various combinations of pH and calcium ion (Ca2+) concentrations using a quasi-constant composition titration method. Under high concentrations of hydrogen ion (H+) and Ca2+, the promoting effect of Ca2+ on the hydrolysis of Na2SiF6 was stronger than the inhibition effect of H+. However, the inhibition effect of H+ on the hydrolysis of Na2SnF6 was stronger than the promoting effect of Ca2+. Na2SiF6 and Na2SnF6 were found to have hydrolysis properties that may make them suitable for use with an acidic calcium phosphate solution in a topical fluoride treatment which forms dicalcium phosphate dihydrate as an intermediate.
authors.affiliation: American Dental Association Health Foundation, Paffenbarger Research Center, Polymers Division, National Institute of Standards and Technology, Gaithersburg, Md.
authors.forename: N
authors.initials: N
authors.lastname: Eidelman
authors.forename: L C
authors.initials: LC
authors.lastname: Chow
mesh_terms: D002118:Calcium / Q000737:chemistry; D005459:Fluorides / Q000737:chemistry; D005460:Fluorides, Topical / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D012824:Silicic Acid / Q000737:chemistry; D012996:Solutions / Q000032:analysis
chemical_list: D005460:Fluorides, Topical; D012996:Solutions; D012824:Silicic Acid; C035907:sodium hexafluorostanate; C004832:hexafluorosilicate; D005459:Fluorides; D002118:Calcium