500mL -- 0.5L,HAc 3/60= 0.05mol
HAc == H+ + Ac-
[H+] = [Ac-] = 0.0005mol/0.5L = 0.001mol/L
[HAc] = (0.05-0.0005)mol/0.5L = 0.099mol/L
K = ([H+]*[Ac-])/[HAc] =(0.001*0.001)/0.099= 1.01*10^(-5)
约等于1*10^(-5)mol/L
(2)NaAc = Na+ + Ac-
〔Ac-〕=0.5mol/0.5L = 1.0mol/L
〔H+〕=K*〔HAc〕/〔Ac-〕
=0.0000101*0.1/1.0
=1.01*10^(-6) mol/L