Q4. Write illustrated notes on TWO of the following: (a) Explain the differences between driven and self-driven electrochemical cells. Give example of a spontaneous system and a non-spontaneous. What is the driving force in the self-driven system and what in the driven system? Explain these in terms of the redox potentials and provide the expression for the Gibbs energy in relation to the cell potentials. (b) How do redox flow batteries operate? Explain their principle and what they have been designed for. What is the driving force? Illustrate your answer with diagrams and equations. Is the system suitable to store large amounts of electrical power? Why? (c) What is cyclic voltammetry used for? How does the electrode potential change with time and what is the response of the system? Show a schematic example that includes a detailed labelled current vs. potential curve. Explain what the criteria for reversible systems are and how the concentration profile of the electroactive species on the surface of the electrode change as the potential moves away from the equilibrium value. Use diagrams and equations to help your explanation. d) Draw a typical polarization curve observed in a hydrogen/oxygen fuel cell (cell voltage vs. current density). The diagram should include the three characteristic regions; kinetic, ohmic drop and mass transport. Write the equation that describes the cell potential and identify the major losses of energy in a fuel cell. ) Explain what is an ion exchange membrane? Give examples where these membranes are used. Explain what the differences between cationic and anionic membranes are. Illustrate the main transport mode of ions inside the ionic membranes based on the NernstPlank equation. Please use diagrams and mathematical expression in your response