In: Chemistry
acid | formula | k1 | k2 | k3 |
arsenic acid | 5.8e-3 | 1.1e-7 | 3.2e-12 | |
carbonic acid | 4.45e-7 | 4.69e-11 | ||
hydrogen sulfide | 9.6e-8 | 1.3e-14 | ||
phosphoric acid | 7.11e-3 | 6.32e-8 | 4.5e-13 |
Determine the pH of a 0.0410 M solution of the following salts. A table of pertinent K values is found to the right. a) Na2S b) Na3AsO4
a) pH of Na2S = 7+1/2(pka2+logC)
pka2 of Na2S = -logka2
= -log(1.3*10^-14)
= 13.89
pH of Na2S = 7+1/2(13.89+log0.0410)
= 13.25
b) pH of Na3AsO4 = 7+1/2(pka3+logC)
pka3 of Na3AsO4 = -logka3
= -log(3.2*10^-12)
= 11.5
pH of Na3AsO4 = 7+1/2(11.5+log0.0410)
= 12.056