Question

To determine the formation constant, Kf, for [Zn(CN)4)2-(aq), 4.00 mL of 1.50 mol/L KCN(aq) and 1.00 mL of 0.0750 mol/L Zn(NO3)2(aq) were combined. The mixture was stirred for 10 minutes to ensure that equilibrium had been reached. A voltaic cell was constructed to determine the concentration of uncomplexed Zn2+ (aq) ions left in solution at the end of the complexation reaction. The [Zn(CN)4]- (aq), Zn2+ (aq), CN (aq) reaction mixture along with a solid zinc electrode served as the anode while a 1.00 mol/L Zn2+ (aq) and Zn(s) was used as the cathode. The measured cell voltage was 0.563 V. Calculate the concentration of Zn2+ (aq) in the anode half-cell by using the Nernst equation. 5.8 x 10-22 mol/L 4.1 x 10-24 mol/L 0 1.1 10-8 mol/l 8.9 x 10-18 mol/L 0 2.6 x 10-12 molt O 7.7 * 10-mol/L 09.3 10-20 mol/l 3.0 x 10-15 mol/L

This is all the information I was given to answer this question.

Answer 1

E_{​​​​​​cell} = -(0.059/2) log(x/1) = 0.563 V

where x is the Concentration of Zn^{​​​​​2+}(aq) in the Anode.

Hence, x = 9.3 x 10^-20 M

Thus, the Correct Option will be :

• 9.3 x 10^-20 mol/L