Final answer:
The non-essential criterion for a good reference electrode is that it is 'easy to make.' Instead, stability and reproducibility of its potential are what make a reference electrode suitable for accurate and consistent potential measurements in electrochemistry.
Step-by-step explanation:
The criteria that is not necessary for a good reference electrode is that 'it is easy to make.' Reference electrodes play a crucial role in electrochemistry for determination of cell potentials, and it is essential that they maintain certain properties to be effective. The most important characteristics of a reference electrode are that it has a relatively constant potential, it has a well-known half potential, and that its half potential does not change with changes in temperature. This ensures the accuracy and reproducibility of measurements in electrochemical cells.
For example, the standard hydrogen electrode (SHE) is a widely used reference electrode with a defined potential of exactly 0 V under standard state conditions. Another important aspect of a reference electrode is that its potential should not be influenced by the properties of the solution to be analyzed, and it should be physically isolated from the solution.
An inert electrode, on the other hand, is an electrode that conducts electrons to and from the reactants in a half-cell but is not itself oxidized or reduced. Inert electrodes are crucial in half-cells where the reactants are in a state that doesn’t allow them to make direct electrical contact with a circuit. Although making an inert electrode might be complex, its production does not define its reference potential quality.