The hydrogen electrode is prepared electrochemically by depositing

Options

A. Platinum on copper metal
B. Silver on platinum metal
C. Platinum on platinum metal
D. Palladium on palladium metal

Answer

C

Explanation

The normal hydrogen electrode or standard hydrogen electrode, which is used as a primary reference, consists of a piece of platinum foil, which is cpateed electrolytically with a very finely-devided platinum known as platinum black to give it a large surface area, suspended in a molar solution of hydrogen ions. Pure hydrogen gas at `1` bar pressure is continually bubbed into the solution to keep it saturated and to expose the soil alternately to gas and solution.
The platinum act as an electrical conductor and also facilitates the attainment of equilibrium between the gas and its ions in solution.
In practice a 1.18 `M` solution of hydrochloric acid is used so that the activity (i.e. the effectivity concentration) of the hydrogen ions in solution is exactly unity.