(a) The current in an electrochemical cell is dependent upon the conditions of the cell. The current is limited by the insufficient rate at which reactants interact with or products removed from the surface of one or both electrodes, this condition is known as concentration polarization.
The current can also be limited by the rate at which electrons are transferred between the electrodes and reactants, known as kinetic polarization. In both conditions the current of the cell is not proportional to the cell potential.
(b) An amperostat is an instrument used in coulometric titrations as it applies a constant current. The instrument functions by detecting a decrease in current within the cell and reacts by increasing the potential supplied to the electrochemical cell until the current is restored.
A potentiostat modifies the supplied potentials to keep a fixed value for the potential between the working and reference electrodes.
(c) Both faraday and coulomb are units assigned to the quantity of charge or electricity. A coulomb is the measure of ampere of current per second, whereas, a faraday is 96,495 coulombs or one mole of electrons.
(d) The working electrode is electrode at which the chemical reaction is occurring. The counter electrode helps this process by supplying electrons to the working electrode. The chemical reaction at the working electrode is not effect by the counter electrode.
(e) For the controlled-potential methods, the electrolysis circuit involves the working electrode and a counter electrode. Whereas, a control circuit adjusts the potential between the working electrode and the reference electrode in.