Why does muriatic acid disolve zinc faster that copper?

Answer 1

Muriatic acid is the old name for hydrochloric acid. Zinc is a much more reactive metal than copper, and, in fact, copper is prevented from reacting with hydrochloric acid because it simply isn't reactive enough.

Answer 2

Corrosion potential is correlated to ionization energy. How easily a metal gives up one or more electrons to become an ion.

There is a whole ranking of metals based on their corrosion potential called the electromotive or Galvanic series. http://en.wikipedia.org/wiki/Galvanic_series. I like it because it helps me look at systems and make some quick judgments.

If I see an assembly built with two metals that are far apart on the list, I know there is a highly likelihood that corrosion will occur. The corrosion may not be present at the time, but trouble will come. And like your zinc and copper, just by knowing their positions in that series, I know something about how they would behave in a corrosive situation like immersion in muratic acid.

Now the test… Magnesium is the lowest metal on that list (Mg < Zn < Cu). How will it react in your muratic acid? Faster or slower than the other two metals?

Answer 3

Because it has a faster reaction rate. And why I don't know.