Question

What is the equilibrium constant for H2CO3(aq)->2H+(aq)+CO3-2(aq)

Answer 1

You will find k1 and k2 listed in tables. k1 is for the first H^+ ionization and k2 is for the second. Your equation is for both at one time. When it is appropriate to use the total ionization equation the Keq is Keq = k1*k2