Amagnesium bar with a mass of 6.8 kg is attached to a buried iron pipe to serve as a sacrificial anode. an average current of 0.025 a flows between the bar and the pipe. what half-reaction takes place at the surface of the magnesium bar?

The half-reaction takes place at the surface of the magnesium bar is the oxidation process (losing of electrons). The chemical equation is as follow:

Explanation:

In the given situation, two reactions take place

1.  On the surface of magnesium bar:

As magnesium bar acts as anode so on the surface of magnesium bar, oxidation take place. Oxidation is a chemical reaction that result in the loss of electrons and oxidation state of magnesium increases to 2 as shown in the following equation:

2. On the surface of iron pipe:

Corrosion is a natural process which results in the deterioration or destruction of materials, in this case, it is iron.