initial molarity of Fe+3 = 10 x 3.48 x 10^-3 / (10 +4 + 6)
                                   Â
= 1.74 x 10^-3 M
initial molarity of SCN- = 4 x 2.84 x 10^-3 / 20
                                   Â
= 5.68 x 10^-4 M
Fe+3Â Â Â Â Â Â Â Â Â Â Â
+Â Â Â Â SCN-Â Â Â
----------------------------> FeSCN2+
1.74 x 10^-3Â Â Â Â Â 5.68 x
10^-4Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
----------------> initial
1.74 x 10^-3-x  5.68 x 10^-4
-x                         Â
x                    Â
-------------------> equilibrium
x = 8.70 x 10^-5 M
equilibrium concentration of Fe+3 = 1.74 x 10^-3-x
                                                    Â
= 1.74 x 10^-3 - 8.70 x 10^-5
                                                    Â
= 1.65 x 10^-3 M
equilibrium concentration of SCN- = 5.68 x 10^-4
-x  Â
                                                      Â
=5.68 x 10^-4 - 8.70 x 10^-5
                                                     Â
= 4.81 x 10^-4 M