Which of the following statements is incorrect?

• In a mixture of solutions containing iron (III) nitrate and potassium thiocyanate both react to form iron (III) thiocyanate solution which red in colour :


Fe3++SCN– ⇌ FeSCN2+(Red)


• Now, when oxalic acid is added to the solution, it reacts with the remaining Fe3+ ions and forms a stable complex ion [Fe(C2O4)3]3- thus concentration of free Fe3+ decreases, therefore by decreasing the red colour of the given solution.


Fe3+ +3 C2O42-⇌ [Fe(C2O4)3]3- .

1