Calculate the thiocyanate concentration at equilibrium if the irone (III) ion concentration is 0.23 M and the complex ion concentration is 0.625 M t equilibrium. Keq= 138M^-1

Answer 1

I will assume the Keq given is for the reaction
Fe^3+ + SCN^- ==> [FeSCN]^2+

K = [FeSCN]^2+/[Fe^3+][SCN^-]
Substitute the numbers in the problem and calculate the only unknown there.