When to use anode/cathode not in the reaction

[Rachel Yu 1G]

In general, how do we know when the cathode/anode that is not in a redox reaction?

For example, in homework problem 6L5 part b, the redox reaction is 2Ce4+ + 2I- -> I2 + 2Ce3+. However, the cell diagram is Pt(s)|2I-|I2||Ce4+, Ce3+|Pt(s). How do we know that the anode/cathode is made up of Pt(s)?

[Michael Nguyen 1E]

You need to use a platinum metal electrode for the cathode/anode when there is no solid metal conductor present in the redox reaction. The platinum electrode allows for electron transfer without affecting the actual redox reaction.

[Katie Kyan 2K]

You'll know when to use an inert electrode like platinum when the reaction doesn't have a metal that allows electrons to be conducted from anode to cathode.

[Jaci Glassick 2G]

You use Pt when electrons can not be conducted from anode to cathode because there is no metal present. Basically, you use Pt when the cathode and anode is aqueous to aqueous instead of solid to aqueous.