Is #HF# a strong acid or weak?

1 Answer
Mar 31, 2017

Answer:

#"Hydrogen fluoride is a weak acid in water............"#

Explanation:

We interrogate the equilibrium:

#HF(aq) + H_2O(l) rightleftharpoons H_3O^(+) + F^-#

#K_a=([H_3O^(+)][F^-])/([HF])=6.3xx10^-4#;

Since the equilibrium lies strongly to the left, we would classify #HF# as a weak acid. Salts of #"hydrogen fluoride"# i.e. #NaF# or #KF# give slightly BASIC solutions in water. Why should this be so?