Use the table of complex ion formation constants to calculate the molar concentration of free Fe^2+ in 0.510M aqueous solution of potassium hexacyanoferrate(II) K4(Fe(CN)6) at 25 degrees celsius.
I know the answer is 1.96*10^-6 m, but I'm at a loss on how to get there.
I've written down the information from the formation constant chart that i need, but again I don't know how exactly to use it.