[TEA1]

Determine equilibrium constant of the following:
Hg²+ + MgEDTA²- ---> HgEDTA²- + Mg²+

Looking at a table formation constants
log Kf of Hg2+ is 21.5
log Kf of Mg2+ is 8.79

So I took the antilog of each and divided Mg/Hg.  Would that be the equilibrium constant?

[AWK]

Write down expression for both Kf, and look what operation is needed for K of your reaction

pKf of your reaction is 12.71