Electrochemistry

posted by .

Hi, I'm in my final year of high school doing an electrochemistry unit and there is a concept I just don't really get. I would appreciate all helps please--

Redox reaction half reactions are:

Oxidation: Zn(s) --> Zn 2+ (aq) + 2e-
Reduction: Cu2+ (aq) + 2e- ---> Cu(s)

In terms of electrodes, Zn in the anode and Cu is the cathode.

Its in a galvinic cell, Zn releases electrons to become Zn2+, but how come the anode of the galviniv cell is negatively charged? If it releases electrons, shouldn't it be Postivively charged?

Also, in terms of porous barriers to maintain electrical neutrality, why are the negative ions (anions) migrating toways the anode and the positive ions (cations) migrate towards the cathode? Shouldn't the opposites attract?

Thank you muchly for all your help!!


OK, it is a matter of definition: Where did you get the statement "In terms of electrodes, Zn is the anode and Cu is the Cathode"? That statement is correct, but it is based on the flow of current. Forget about electrons. The world long ago in physics and chemistry defined the direction of current flow as the direction of Positive charge carriers (even though in wires they don't exist). So with this DEFINTION of current flow, the definition that the anode is the terminal where current flows in fits: Zn is the place current flows in. If current is flowing inward, then it is OK for electrons to flow the opposite way.
Forget about electrons having anything to do with current flow direction.
If current (positive) is flowing in, then Zn must have a negative charge, or in physics terms, have a lower potential.

Negative ions migrate towards the Zn++ cations, which are leaving the Zn anode. See the picture here:
http://www.jiskha.com/display.cgi?id=1168798599

Another way of saying it, although Bob Pursley was eloquent, is---
By definition, the anode is where oxidation occurs.
Zn==> Zn++ + 2e

Therefore, Zn is losing electrodes and it is the anode by definition.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Electrochemistry

    I have an electrochem based question. I'm trying to solve for E* based on a chart in my book. I know the equation for solving this is E*= E*ox + E*red. The chart in my book gives a list of reactions and a E*red value. My teacher told …
  2. Chemistry

    I'm confused with this question as I don't understand how to write the reactions. Here is the question if you could please help me with this question or just even give me an example on how to do it. I would really appreciate it. Thank …
  3. Chem I

    Ok one more! Write the balanced equations and assign oxidation numbers to all atoms in these two reactions involving iron. If the effective oxidation number of any particular atom changes during the reaction then a redox reaction has …
  4. chemistry

    Use the following steps to balance the redox reaction below: Mg + Au+ Mg2+ + Au -Write the oxidation and reduction half-reactions. Make sure each half-reaction is balanced for number of atoms and charge. -Multiply each half-reaction …
  5. chemistry-balanced redox equations

    Use the following steps to balance the redox reaction below: Mg + Au+ Mg2+ + Au a. Write the oxidation and reduction half-reactions. Make sure each half-reaction is balanced for number of atoms and charge b. Multiply each half-reaction …
  6. chemistry

    Using the half-reaction method, balance the redox reaction below. Show your work; partial credit will be given. I- + Br2 → IO3- + Br- Write the reduction and oxidation half-reactions. Balance them for atoms. Balance each of the …
  7. chemistry - equilibrium Help

    you observed that very little corrosion occurred on the nail immersed in NaOH(aq) solution. This observation is difficult to explain from an electrochemistry perspective since electrochemistry principles predict a spontaneous reaction …
  8. Chemistry: check answers

    Please check. Thank you. 2. What is the reduction half-reaction for the following unbalanced redox equation?
  9. General Chemistry

    Balance the following redox reaction in acidic and basic solutions: Fe(OH)2(s) + O2(g) --> Fe(OH)3(s) These are the steps my instructor gave us to balance redox reactions: 1. Divide into 1/2 rxns (reduction & oxidation) 2. Balance …
  10. Chemistry

    separate this redox reaction into its component half-reactions. O2 + 4Cu-->2CuO Oxidation half-reaction: ?

More Similar Questions