Question

A cell composed of a platinum indicator electrode and a silver-silver chloride reference electrode in a solution containing both and has a cell potential of V. If the silver-silver chloride electrode is replaced with a saturated calomel electrode (SCE), what is the new cell potential?

Answer 1

Step-by-step explanation:

Let us assume that the solution contains both
`Fe^(2+)` and
`Fe^(3+)` which has a cell voltage of 0.719 V.

Therefore, voltage of cell contains both Ag/AgCl reference electrode where
`Fe^(2+)/Fe^(3+)` electrode is 0.719 V.

As,
`E_(cathode) - E_(anode)` = 0.719 V

It is known that potential of the silver-silver chloride reference electrode is 0.197 V.

Hence,
`E_(anode)` = 0.197 V. Now, calculate
`E_(cathode)` as follows.

`E_(cathode) - E_(anode)` = 0.719 V

`E_(cathode) - 0.197 V` = 0.719 V

`E_(cathode)` = 0.916 V

Now, voltage of the cell that contains both calomel reference electrode and
`Fe^(2+)/Fe^(3+)` electrode as follows.

`E_(anode)` = calomel electrode = 0.241 V

Voltage of cell =
`E_(cathode) - E_(anode)`

= 0.916 V - 0.241 V

= 0.675 V

Thus, we can conclude that 0.675 V is the new voltage.