Which element is less active than hydrogen in cathodic protection systems?

In cathodic protection systems, the relative electrochemical activity of metals is a critical factor in determining their effectiveness as sacrificial anodes. When considering which element is less active than hydrogen, we look at the standard electrode potentials of these materials.

Copper has a standard electrode potential of approximately +0.34 V, which indicates that it is more noble and less cathodic than hydrogen, which has a potential of 0 V. This means that, in terms of electrochemical reactivity, copper does not corrode in a standard electrolytic environment when compared to hydrogen. Therefore, in the context of cathodic protection systems, copper is the least active of the choices provided, making it suitable for use in applications where lower reactivity is beneficial.

On the other hand, zinc, magnesium, and aluminum have more negative electrode potentials, making them more active than hydrogen. They readily corrode and sacrifice themselves to protect more noble metals from corrosion. This characteristic is crucial for their roles as sacrificial anodes in cathodic protection.

In summary, copper's position on the electrochemical series makes it less active than hydrogen, qualifying it as the answer to the question about which element is less active in the context of cathodic protection systems