Question

In hydrogen evolution type of corrosion with respect to hydrogen electrode which of the following is correct.
A. the metal with more negative SRP value under the given conditions
B. the metal with more positive SRP value under the given conditions
C. the metal with both negative and positive SRP values
D. All of the above

Answer 1

Hint: The standard reduction potential is relative to a standard hydrogen electrode which is the reference electrode giving a potential of 0.00 V. The element which has a high value of reduction potential value gets reduced whereas the element that has a low reduction potential value will get oxidized.

Complete step by step answer:
The reduction potential is also known as redox potential or oxidation-reduction potential. It measures the ability of a chemical compound to accept electrons and itself gets reduced. It is measured in terms of a volt (V).
A series of half cells and electrodes are assembled in their increasing standard oxidation potential value or in decreasing standard reduction potential value. This series is called electrochemical series or electromotive force series.
The compounds which have stronger reducing power than hydrogen are put below the hydrogen and possess negative standard reduction potential value and the compounds which have weaker reducing power than hydrogen are put above hydrogen and they possess positive standard reduction potential.
The metals which are present below the hydrogen electrode will tend to reduce the hydrogen ion to form hydrogen gas whereas the metals which are present above hydrogen will not reduce hydrogen ion.
Metals like iron, zinc lie below the hydrogen electrode and have more negative standard reduction potential value.

Therefore, the correct option is A.

Note:
The standard reduction potential is determined under standard conditions that are temperature should be 25 degrees Celsius, 1 molar concentration of each ion take part in the reaction, 1 atm partial pressure is used and metal should be in its pure state.