Question

a) "An aqueous solution of iron (III) nitrate is mixed with an aqueous solution of potassium thiocyanate, to provide an aqueous solution of iron (III) thiocyanate and potassium nitrate." Write a balanced reaction scheme for the chemical reastion just described.

b) Write the net ionic equation

c) Predict the outcome of adding iron (III) nitrate to the test tube from reaction above.

d) Predict the outcome of adding potassium thiocyanate to another test tube of the iron (III) thiocyanate solution.

Answer 1

The reaction equation is represented as

Fe(NO₃)₃ (aq) + KSCN (aq) Fe(SCN)₃ (s) + KNO₃ (aq)

The balanced equation is

Fe(NO₃)₃ (aq) + 3 KSCN (aq) Fe(SCN)₃ (s) + 3 KNO₃ (aq)

The ionic equation is represented as;

Fe⁺³ (aq) + 3NO₃^-(aq) + 3 K⁺(aq) + 3 SCN^-(aq)    Fe(SCN)⁺²(aq) + 2SCN^-(aq) + 3K⁺(aq) + 3 NO₃^-(aq)

Cancelling out the spectator ions produces:

Fe⁺³ (aq) +  SCN^-(aq)    Fe(SCN)⁺²(aq) [net ionic equation]
(blood red complex)

Adding iron (III) nitrate will react with SCN^- to form the Fe(SCN)⁺²(aq) (blood red complex).

Adding potassium thiocyanate will also form the Fe(SCN)⁺²(aq) (blood red complex) as per the net ionic equation shown above.