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This is how I understand the working of an electrochemical cell: We have two beakers, the first contains a zinc road immersed in zinc sulfate solution and the second one is provided with a copper road dipped in the copper sulfate solution. We then connect both the roads with a wire fitted with a bulb and we have our bulb lightening. I was told that the zinc road is ionizing and producing zinc ions and electrons. These electrons then go towards the copper road through the wire and react with the copper ions there in the copper sulfate solution. This setup will work fine until our zinc road is consumed completely. Now following questions pop up into my mind while thinking about this:

  1. Why does the zinc road immersed in its sulfate solution gives off electrons whereas no such thing happens with the copper road?
  2. Why do the electrons travel along the wire at all? What the heck do they care about and why only the electrons? ( I know they are charged particles ) since there are other charged particles too ( Zinc ions, sulfate ions, copper ions ).

Please provide an answer from a layman's perspective.

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  • $\begingroup$ The driving force is diffusion: random walks which result in zinc ions moving to an area with lower concentration. $\endgroup$ – Pieter Jan 18 '18 at 9:02
  • $\begingroup$ To answer your second question: if the zink rod indeed produces electrons, then they will "push each other away" by repulsion and thus start moving up through the wire. Otherwise the same question would be asked about any normal battery with a wire connected end-to-end. $\endgroup$ – Steeven Jan 18 '18 at 9:04
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In layperon's terms you can think of the ingredients of the cell, the copper and the zinc, undergoing chemical reactions.
Zinc can combine with oxygen to form zinc oxide and in this type of reaction, which is called an oxidation reaction, zinc atoms lose full control of some of their electrons.
Copper undergoes a similar reaction with oxygen to form copper oxide.

Oxygen does not have to be involved in the oxidation process and the term oxidation is more generally used when an atom loses full control of some of its electrons and reduction is the term used when an atom gains some control of more electrons than it originally had.

The cell you describe is called a Daniell cell and you have two completing electrodes one made of zinc and the other of copper which have the possibility of being oxidised.

In this cell the zinc is more "reactive" and the oxidation reaction (losing full control of electrons) for zinc at the zinc electrode can be written as follows

$\rm Zn \rightarrow Zn^{2+}+ 2 e^-$

So you now have a zinc rod which has a surplus of electrons - it is negative - and these elections can move away from one another by flowing through the conducting wire towards the copper electrode.

At the copper electrode the copper ions in solution combine with these electrons which have moved through the wire and neutral copper atoms are deposited on the copper electrode.
This is a reduction reaction.

$\rm Cu^{2+} + 2 e^- \rightarrow Cu$

So the copper is "forced" into the reduction reaction by the zinc undergoing an oxidation reaction.

Having an understanding the electrochemical series will perhaps help you understand the workings of such a cell?

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