Need help with my question in Electrochemistry

Question

Calculate the Zn conc. of Zn/Zn++ // Cl/Cl^- 0.1M Emf=2.21v

answers:

a)0.1M

b)0.2M

c)0.05M

d)0.15M

Answer 1

Use the Nernst equation. Since no temperature is given in the problem, assume it to be 25ºC and use a modification of the Nernst equation for 25ºC which is E_cell = Eº_cell - 0.0951/n log Q where n is the number of electrons transferred. You'll need to look up the standard reduction potentials for Zn and Cl and calculate the Eº. Since you are given the E_cell as 2.21 V, and Cl concentration of 0.1 M, you can solve for log Q and hence for [Zn].