Hydrogen fluoride behaves as a weak acid in solution. Two equilibria influence which fluorine containing species are present in solution.
HF (g) + H2O (l) --> H3O+ (aq) + F- (aq) (Ka= 1.1*10^-3)
F-(aq) +HF (g) --> HF2- (aq) (Ka= 2.6*10^-1)
a. Is fluoride in pH 7.00 drinking water more likely to be present as F- or HF2-
b. What is the equilibrium constant for this equilibrium?
2HF (g) + H2O (l) --> H3O+ (aq) + HF2- (aq)
c. what are the pH and equilibrium concentration of HF2- in a .170M solution of HF?