[bhonris]

Hi there, newbie here.

As you may know, you can generate a small amount of electricity when you put copper and zinc into saltwater and connect the two metals with wire.

From my understanding, this process is the same as putting in Zinc and Magnesium instead of Zinc and Copper. Since Magnesium is more reactive than Zinc, that Magnesium reacts with water to form Mg++ faster than the rate at which Zinc reacts with water to form Zn++, the Magnesium plate becomes more negative at a faster rate than Zinc, thus the net electron movement in the wire is that from magnesium to zinc.

However, I have put zinc and magnesium into saltwater and connected them with a wire. After about fifteen minutes, I took both metal strips out of the solution. I then compared the magnesium that has undergone the process with a new, unused piece of magnesium, where I found a significant potential difference. According to what I explained from above, the reason for the potential difference is that the Mg that has undergone the process has changed in reactivity, thus implying that the Zn has coated the Mg. This, however, goes against the theory of the voltaic cell in which the more reactive metal dissolves into the solution. In other words, I expected Mg to dissolve, which is not consistent with the results I have which the Mg is coated by Zn.

What is going on? Any help will be appreciated

Thanks

[Hunter2]

I don't think its coated, I think you get some oxide layer.