Question

Engineers attach a sacrificial anode to the copper pipe. To use impressed current cathodic protection, they must attach a battery between the cathode and anode. Which material should the positive side of the battery be attached to? Explain how you know.

Answer 1

Answer:

SEE EXPLANATION

Explanation:

Cathodic protection means the attachment of a sacrificial anode which corrodes instead of the protected metals. This is common in iron and zinc system.

The sacrificial anode makes use of a metal more active than the base metal to “sacrifice” ions. These “sacrificial anodes” (usually alloys such as magnesium, aluminum, or zinc) have a much stronger electrochemical potential.

This is because current now flows in the opposite direction due to the DC.

The sacrificial anode may be positive

The protected metal may be the negative electrode

Answer 2

For example couple Cu/Zn.
The electronegativity of zincum is less, than at copper.  

(Cu, cathode, -) 2H₂O + 2e⁻ → H₂ + 2OH⁻
(Zn, anode, +) Zn → Zn²⁺ + 2e⁻