Question

A galvanic cell is built at 25 ºC using a Cr electrode inside a 2.0 M Cr3+ solution (100 mL) and a Ni electrode inside a 0.5 M Ni2+ solution (100 mL). Both solutions are connected with a salt bridge.

a) (0.5 p) Write the cell notation and the global redox reaction. Indicate the anode and the cathode of the cell. Determine the cell potential with the given concentrations.

b) (0.5 p) Determine how many of the previous cells must be employed in order to carry out the electrolysis of molten sodium chloride, according to the following reaction: NaCl (molten) ↔ Na (molten) + ½ Cl2 (g) Assume that the concentrations of the reactants and products in the electrolysis process are 1 M.

c) (0.5 p) Calculate the potential of the galvanic cell after it has produced an intensity of 12.865 A for 10 minutes.

Data: E0 (Cr3+/Cr) = -0.74 V; E0 (Ni2+/Ni) = -0.25 V; E0 (Cl 2/Cl - ) = 1.36 V; E0 (Na + /Na) = -2.71 V; F = 96500 C mole - -1

Answer 1

A redox couple having higher reduction potential has higher reduction tendency and hence acts as cathode and the one having lower potential acts as anode.