If a buffer system containing hydrofluoric acid and fluoride (pKa = 3.17) initially has a pH of 3.22 and base is added until a new pH of 4.69 is obtained, how has the ratio of fluoride to hydrofluoric acid changed? A.
from 1.12 : 1 to 33.1 : 1
B.
from 1 : 1.12 to 33.1 : 1
C.
from 1 : 1.12 to 1 : 33.1
D.
from 1.12 : 1 to 1 : 33.1

The answer is 1.82 j/g°c                  

Answerthe half-reaction having the greatest tendency to occur at the anode:     i₂(aq) + 2e⁻  ⇄ 2i⁻  ;   e = +0.53 v======oxidation occurs at the anode. we must therefore find the half-reaction with the greatest tendency to oxidize.the given values of e are reduction potentials (the form of the half-reactions are of reduction).the lower the reduction potential, the higher the potential to oxidize. the half-cell with the lowest reduction potential will have the greatest tendency to oxidize at the anode.the half-reaction having the greatest tendency must be    i₂(aq) + 2e⁻  ⇄ 2i⁻    e = +0.53 vbecause its reduction potential is the lowest out of the three.