[mikewday]

I understand the basic process that allows an electrical current to flow if you place a zinc and a copper rod into something like a lemon or apple. I am looking to fill in some of the blanks...

I know that copper can easily give up one electron and zinc can easily give up 2 electrons. These outer electrons are hard to "hold onto".

Copper contributes electrons, Zinc dissolves into the solution (Zn+2) and the "extra" electrons left in the zinc rod can travel through a connecting wire (and perform some work) on its way to fill in the electron "gaps" in the copper rod.

Question...
Does the reaction start by Copper giving up an electron to the acid molecule (such as maleic acid) ... where H+ breaks from the malic acid molecule and gets an electron from copper. Two Hydrogens combine to make H2 gas.
Or, as some things I have read state... the Zn+2 dissolves into solution and that starts the process?

What I think happens is that the reaction starts because maleic acid that is close to the copper loses one or two H+ because they can easily grab an electron from copper and form H2 gas...

What is maleic acid with the two missing H+ called?

The maleic acid molecule now has a slightly negative charge.
When this negatively charged molecule comes close to the zinc rod, it attracts the Zn+2 into the solution.

Does Zn+2 create an ionic bond with the maleic acid that has lost the 2H+ ?

So, as the reaction continues, malic acid keeps causing copper to lose electrons and zinc keeps entering the solution... There are electrons left in the Zinc rod and "missing" electrons in the copper rod so... attaching a wire between them allows the electrons to "flow" as if going from high pressure on the zinc side (lots of extra electrons) to low pressure (missing electrons) on the copper side (just an analogy).

Is this correct?
I just want to know what starts the reaction and to be able to visualize the atoms and molecules moving around and all of the interactions.

Thanks!

 

[Borek]

Copper loses 2 electrons, just like Zn does (it can lose 1 electron only, but it is less likely). But it doesn't matter here.

The reaction is between Zn and H⁺, copper acts just as an inert electrode - it doesn't react. Maleate is just a counterion.

[mikewday]

Okay... this is where I get confused. So, the maleic acid reacts with the Zinc. Hydrogen gas (H2) is formed as well as maleate (C4H2O4Zn)?

So, why do the electrons move through the wire to the copper rod?

Is it that the maleic acid drops its 2H+ in exchange for the Zn+2 and then the "lose" H+ pull their electrons from the copper side instead of the Zinc side because it is easier for copper to give up its electrons?