Chapter 19.8, Problem 1Q

Interpretation Introduction

Interpretation: It has to be explained the reason for if the paint is placed between the copper and the zinc, the zinc will still corrode in seawater, but it will not protect the copper from corrosion.

Concept introduction: Corrosion is a natural process. The destruction of metals by electrochemical reaction with water and oxygen in the air.

Sacrificial anodes are highly active metals that are used to prevent a less active metal surface from corrosion.

The loss of electrons is called oxidation whereas the gain of electrons is called reduction.

In an electrochemical cell, at anode oxidation takes place and at cathode reduction takes place.

The copper is oxidized by air in seawater. The chemical reaction is written as,

    $\text{Cu}\left(\text{s}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)+\frac{1}{2}{\text{O}}_{\text{2}}\left(\text{g}\right)\to \text{Cu}{\left(\text{OH}\right)}_{\text{2}}\left(\text{s}\right)$