Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I don't understand what causes redox reactions to occur.

  1. Oct 21, 2011 #1
    For example, on this website http://www.chemguide.co.uk/physical/redoxeqia/combinations.html in the second diagram from the top, it shows that *if a high resistance voltmeter is placed between two pieces of metal, zinc and copper, the zinc metal will accumulate a build up of electrons.* Then when the resistance is relieved, the electrons will necessarily flow to the copper metal, which I understand.

    What I'm confused about is: why do electrons build up on the zinc metal in the first place, and where do the electrons come from?

    Thank ya.
  2. jcsd
  3. Oct 22, 2011 #2


    User Avatar

    Staff: Mentor

    This is exactly the same question you can ask for every chemical reaction - why does it go the way it does. Short answer is - because it is thermodynamically favorable. In most cases that means that products have lower energy than reactants (although this is oversimplification).

    From the half reaction - Zn "prefers" to be in the ionic form, and some of the atoms "jump" into solution leaving their electrons in the bulk of the metal.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook