Consider an electrochemical cell based on the half-reactions Ni²⁺(aq) + 2 e⁻ → Ni(s) and Cd²⁺(aq) +2 e⁻ → Cd(s).
(a) Diagram the cell, and label each of the components (including the anode, cathode, and salt bridge).
(b) Use the equations for the half-reactions to write a balanced, net ionic equation for the overall cell reaction.
(c) What is the polarity of each electrode?
(d) What is the value of E°_cell?
(e) In which direction do electrons flow in the external circuit?
(f) Assume that a salt bridge containing NaNO₃ connects the two half-cells. In which direction do the Na⁺(aq) ions move? In which direction do the NO₃⁻(aq) ions move?
(g) Calculate the equilibrium constant for the reaction.
(h) If the concentration of Cd²⁺ is reduced to 0.010 M and [Ni²⁺] = 1.0 M, what is the value of E_cell? Is the net reaction still the reaction given in part (b)?
(i) If 0.050 A is drawn from the battery, how long can it last if you begin with 1.0 L of each of the solutions and each was initially 1.0 M in dissolved species? Each electrode weighs 50.0 g in the beginning.