(a) Early fluoridation of municipal water supplies was done by dissolving enough sodium fluoride to achieve a 1-ppm concentration dfluoride ion. Convert 1.0 ppm F F to percent by mass Fand molality of NaF [Wt Sample Problem [3.2]. (b) Calculate the boiling pitr and freczing point of a solution made by dissolving 4.10gNaF in 100mLH2O (For water. d=1g/mL ) (ke Sample Problem 13.6]. (c) Miny fluoridation facilities now use fluorosilicie acid instead of sodium fluoride. Fluorosilicic acid typieally is distributed as a 23\% (1.596-in) aqueous solution. Calculate the van't Hoff factor of fluorosilicic acid given that a 23% solution has a freeaing point of 15.5C [ku Sumple Problerii 13.7]. (d) The density of 23% fluorosilicic acid is 1.19g/mL. Given that the osmotic pressure of lissolution at 25C is 242atm, calculate the molar mass of fluorosilicic acid (iet Sample Problems 13.8 and 13.9]. (c) Hydrofluoric aUd (HF) is another compound that can be used in the fluoridation of water. HF is a weak acid that only partially ioniyes in solution. Win aqueous solution that is 0.15M in HF has an osmotic pressure of 3.9 atm at 255C, what is the percent tonization of HE at this cosentration [141 Sample Problem 13.11]