posted by Christine
Given the following acid dissociation constants, which acid has the strongest conjugate base?
a. HCN Ka = 6.2 x 10-10
b. HOCl Ka = 3.0 x 10-8
c. HIO3 Ka = 0.17
I believe the answer is HCN it has the lowest Ka and is the weakest acid.
Kb = Kw/Ka = ?
Larger Kb means stronger base. I put in this extra step so as not to confuse Ka and Kb.
The weakest acid should be the strongest base.
HCN Kb = 1.0 x 10^-14/6.2 x 10^-10 = 1.61 x 10^-5
HOCl Kb = 1.0 x 10^-14/3.0 x 0^-8 = 3.3 x 10^-7
HIO3 Kb = 1.0 x 10^-14/.17 = 5.88 x 10^-14
The strongest Kb appears to be HCN. Is this correct?
Are you doing AP Chem? I can help