" A solution of NaF will have a higher pH than HF". Why is this statement true? Please explain ?

Question

" A solution of NaF will have a higher pH than HF". Why is this statement true? Please explain ?

Answer 1

stn is not correct.  Fluoride is the conjugate base of the weak acid HF

( Ka ~ 10^-4 ). Conjugate bases of weak acids are moderately stong to quite strong bases ( depending upon how weak the acid is ). This means that these bases will compete with OH^-1 for protons ( they will strip protons from water maing the weak acid and some OH^1 ) This OH^1 will raise the pH. In the case of NaF., since it is the conjugate base of HF which is about 10 fold stronger than acetate..F^-1 will be 1/10th as strong a base so it will hydrolyze to produce a solution in the high  7s to low 8s  in pH.

Answer 2

NaF will dissociate more than HF, causing the number of H+ ions to increase.  This lowers the pH.  HF is a highly corrosive acid, but because the bond is so strong, it is considered a "weak" acid.