Question

Hi. can some one please explain me the solution for this question. the correct answer is A. thanks.

6. What is the concentration of Co(aq) ions in the solution made by adding water to cobalt(II) nitrate (0.50 mol) and ethylenediamine (3.0 mol) so that the final volume of solution is 3.0 L? The Kb of Co(en)31 is 1.0 x 1014 a) 1.3 x 10M b) 1.5 x 10 M c) 2.9 x 10-'M d) 3.3 x 10M e) 8.7 x 10'M

Answer 1

Now solve the above equation for x.

SOLUTION : Initial conc. of cott (aq) = no. of moles volume of solution 0.5 3 mol L Initial cone of = 0.17 M ethylenediamine = 3 mol 32 IM Now, the chemical equation is + 3 en - [ Co (eu)3] 2+ Co²+ (aq) Initial cone 0.17 M IM + κ Μ - 32 M -x M change (0.17-x (1-3x)" Conc at Equilibrium Now, Kstab 1.0 X 104 (0.19 - (1-3x) 3 (Curen)

The final concentration of Co(II) ion = 0.17- x