Problem Set 7

1. For a galvanic cell at 298 K and made using nickel and cadmium electrodes immersed in solutions with a Ni²⁺ concentration of 0.15 M and a Cd²⁺ concentration of 0.5 M respectively:

a) Calculate the voltage for this cell if both solutions were at 1.0 M concentrations.

b) Calculate the voltage for this cell at the given solution concentrations.

c) Write the equation for the oxidation reaction that spontaneously occurs.

d) Write the equation for the reduction reaction that spontaneously occurs.

e) Write the equation for the overall reaction that spontaneously occurs.

f) Write an equation for Q for the overall reaction.

g) Calculate the change in Gibbs Free Energy for the overall reaction.

h) Determine the value of the equilibrium constant for the overall reaction.

i) Draw a diagram of the galvanic cell and show how the electrons flow, along with the reaction that occurs at each electrode.

j) Predict how the masses of each electrode change over time.

k) An Ampere (A) unit is used to measure electrical current; one Ampere represents a current flow of one Coulomb of charge per second. If a current of 10 mA flows for 30 minutes in the galvanic cell above, calculate the change in mass for each electrode.

1. Calculate the voltage and change in Gibbs Free Energy associated with the oxidation of NADPH to NADP⁺ that is coupled with the reduction of O₂ to water. Assuming that the endergonic conversion of ADP to ATP has requires 30.2 KJ of Gibbs Free Energy, determine the number of moles of ADP that can be spontaneously converted to ATP through the oxidation of a mole of NADPH with oxygen.