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Help:Why do electrons go from negative to positive?

  1. Aug 4, 2015 #1
    Hi,

    I'm confused and need some help.

    What I thought happens in a battery is that the anode (the positive electrode) attracts the anions, it then goes through oxidation by taking the electrons and those electrons move through the closed circuit to the cathode and reduction is done. If that is the case isn't the electrons going from the positive electrode to the negative electrode? Thank you.
     
  2. jcsd
  3. Aug 4, 2015 #2
    In a battery, the anode is negative electrode, for anode is the electrode where oxidation happens, hence also where the electrons emit.
     
  4. Aug 4, 2015 #3
    Besides, after electrons are back to cathode(positive electrode), it will be pushed to the other electrode, that is, anode. Here what you said still happens: electrons go from positive to negative, which depends on the non-conservative force the battery provides.
     
  5. Aug 4, 2015 #4
    Thank you for your prompt reply. I couldn't get an answer from other websites :(. I don't understand how the anode is negative. I could be reading this wrong but on wikipedia it says that it's positive. https://en.wikipedia.org/wiki/Primary_cell.

    If it was negative how does it go through oxidation? Can cations go through oxidation? I'm new to all of this so any feedback would be appreciated. Thank you.
     
  6. Aug 4, 2015 #5
    It's at the very bottom of the wikipedia page. The title is "terminology".
     
  7. Aug 4, 2015 #6
    The anode is defined as an electrode where oxidation happens. For electrons, the negative electrode has a lower potential (with respect to the positive electrode), so electrons have a larger electric potential energy there. Then of course, electrons will be attracted to the positive electrode, no matter you explain it with Coulomb's electric force or electric potential energy. The electrons emit, the electrode is oxidized, so this electrode is anode.
    You should caution that the definition of anode and cathode is different from that of positive and negative electrodes.
     
  8. Aug 4, 2015 #7
    Let's talk in lamens terms, I'm getting confused. To start of with oxidation is the removal of electrons or losing electrons. The only thing I can think of is that the anions gets attracted to a positive electrode and then oxidation occurs. Reduction happens at the other side the negative electrode.
     
  9. Aug 4, 2015 #8
    If this is the case why isn't the electrons going from positive to negative? I'm sorry to be ignorant. I don't understand and it's confusing.
     
  10. Aug 4, 2015 #9
    The oxidation of the anions occurs so then simultaneously the reduction of the positive electrode happens, so the positive electrode is cathode. Right?

    In fact, however, that's not what really happens in a battery. The oxidation and reduction is happening every time on the both electrodes.
     
  11. Aug 4, 2015 #10
    I'm confused. How does oxidation work from the negative electrode? It only attracts cations. It would make sense if that cations can go through oxidation but what I thought is that it isn't possible or is it?
     
  12. Aug 4, 2015 #11
    The negative electrode emits electrons, right? At the same time, it is also being oxidized! For that is just the definition of oxidation: throwing out electrons.
     
  13. Aug 4, 2015 #12
    Sorry deleted my other post. What I meant to say is that when oxidation occurs at the negative electrode what ion is losing the electrons?
     
  14. Aug 4, 2015 #13
    When anode loses a electron, the battery will provide it one, based on the potential of battery,for it's a circuit.
     
  15. Aug 5, 2015 #14

    DrDu

    User Avatar
    Science Advisor

    Usually, it is not an ion that looses electron here but the electrode itself. E.g. zinc may dissolve forming zinc cations,
    ##\mathrm{Zn \to Zn^{2+} +2e^-}##, leaving two electrodes on the anode which charges up negatively.
    The driving force for this reaction to occur is not the electric potential, but the chemical potential which reflects the relative chemical stability of the Zn cations in relation to Zn metal.
     
  16. Aug 14, 2015 #15
    Whether, it is a battery (source of electrical energy) or an electrolysis cell (sink of electrical energy), oxidation occurs at the anode and reduction occurs at the cathode in an electrochemical cell. To understand the motion of positive and negative charges through the circuit, it is better to consider a battery connected across a load such as a light bulb*.

    In this case, oxidation occurs at the anode, releasing electrons into the anode and ions (cations) into the electrolyte. The electrons move from the anode through the external circuit to the bulb and thence to the cathode of the battery where the reduction occurs there by the electrons combine with the cations that reach the cathode through the electrolyte of the battery, thereby completing one unit of cell (battery) reaction.

    Now, we can consider a battery connected across an electrolysis cell.

    In this case too, oxidation occurs at the anode of the battery, releasing electrons into the electrode and ions (cations) into the electrolyte. The electrons move from the anode through the external circuit to the cathode of the electrolysis cell at which reduction occurs consuming the electrons and the cations, that reach the cathode after travelling from the anode of the electrolysis cell, through the electrolyte. The ions released into the electrolyte at the anode of the battery move to the cathode through the battery electrolyte and get reduced by receiving the electrons that reach there from the anode of the electrolysis cell where they were released in the oxidation reaction of the electrolysis cell.

    Thus electrons travel from anode of the battery to cathode of the electrolysis cell; as also from the anode of the electrolysis cell to the cathode of the battery through the electronic conductors of the circuit. Concomitantly, positive ions move from the anode to the cathode through the electrolyte of the battery, and, from the anode to the cathode through the electrolyte of the electrolysis cell.

    * You will be confused if you consider a battery connected across an an electrolysis cell in the first attempt itself.

    P. Radhakrishnamurty
     
  17. Aug 14, 2015 #16
    I missed mentioning in my above reply that the negative terminal of the battery is the anode of the battery, as for example, the Zn can in the torch cell (primary) battery, at which oxidation of Zn occurs. This terminal is connected to the electrode, called as the cathode, of the electrolysis cell at which reduction occurs.
    P. Radhakrishnamurty
     
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