Principles of industrial electrochemistry

Question

Principles of Industrial Electrochemistry

Consider a cell consisting of a silver wire coated with solid silver chloride and a zinc wire in an aqueous solution of zinc chloride at 25^oC.

a)   Calculate the reversible potential difference between the two wires when the activity of dissolved zinc chloride is 0.01 molal (mol/kg H₂0). Indicate the direction of the spontaneous reaction and the sign of the electrodes.

b)   Calculate the reversible potential difference between the two wires when the electrolyte is saturated with an excess of solid zinc chloride. Determine the activity of dissolved zinc chloride in a saturated solution.

Standard chemical potentials at 25^oC:

AgCl (crystal)                            m^o = -109.8 kJ/mol

ZnCl₂ (crystal)                            m^o = -369.4 kJ/mol

ZnCl₂ (dissolved in H₂0)            m^o = -409.5 kJ/mol