posted by alexis .
If K = 1.8 x 10 for HC2H3O (aq) <=> H+(aq)+C2H3O2-(aq), and 100 mL of aqueous solution has [HC2H3O2] = 0.50 M, [H+] = 0.090 M, and [C2H3O2-] 0.0010 M, is the system at equilibrium?
I think you omitted a -5 from the 10^-5 for Ka
HC2H3O2 ==> H^+ + C2H3O2^-
Ka = (H^+)(C2H3O2^-)/(HC2H3O2)
Plug in the values given in the problem and see if you get Ka. If you do then the system is at equilibrium. If not, the system is not at equilibrium.