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I was a reading a book that a senior gave me, it said that redox is a type of reaction in which both reduction and oxidation take place. I know about oxidation but not reduction. After googling reduction reaction I found it's simply just the opposite. But then how can a reduction and oxidation take place together? It would be better if you put forth some examples.

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  • $\begingroup$ In a redox reaction, one compound gives up electrons. These electrons need to go somewhere, which is another compound. The compound that gives up electrons is oxidized and the compound that receives the electrons is reduced. An example is iron rusting: $2Fe + O_2 \rightarrow 2 FeO$. Iron loses 2 electrons which oxygen takes. $\endgroup$ – LDC3 May 11 '14 at 19:11
  • $\begingroup$ How can they not take place together, really? $\endgroup$ – Ivan Neretin Apr 18 '16 at 6:11
  • $\begingroup$ @IvanNeretin An electrochemical cell is the only way to separate them in space. But, unless one is prepared to admit some capacitive charging, it's not possible to separate them in time. $\endgroup$ – hBy2Py Apr 8 '17 at 17:18
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I think you mean Redox, which is a portmanteu of Reduction-Oxidation. An easy example of redox is the Haber process (nitrogen and hydrogen form ammonia)

$$\ce{N2 + 3 H2 <=> 2 NH3}.$$

In the Haber process the nitrogen is reduced (the oxidation state changes from $0$ to $-3$), and the hydrogen is oxidized (the oxidation state changes from $0$ to $+1$). In that redox reaction, both oxidation and reduction take place, as you said.

There's no oxidation without reduction and vice-versa. The electrons lost in oxidation have to go somewhere! If they wouldn't, then there's no reason for the reaction to occur in the first place.

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    $\begingroup$ Actually the Haber process is a pretty complicated equilibrium. A simpler redox reaction is $$\ce{Zn + FeCl2 <=> ZnCl2 + Fe v}.$$ $\endgroup$ – Martin - マーチン May 12 '14 at 8:26
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    $\begingroup$ I read this example from my first chemistry book as an introduction to redox, so I figured I could just use the same one. The process as a whole is complicated, but it doesn't really matter here because we're trying to explain what a redox is, so we just use the first products and last reactants (instead of the whole pathway). Also since most people learn about lewis structures and covalent bonds first, it might be better to explain things with nitrogen and hydrogen. I don't think it makes a difference though. $\endgroup$ – Gaspa79 May 12 '14 at 15:06
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Redox reactions are the results of different electron affinities between atoms of different eletronegativities. THe electrons in mind as ONLY the valance electrons

In the case of CO2. Carbon is in a most very oxidized state. Why. Because the Oxygens are electron hungry and withdrawing 1 valance electron from carbon each. This process describes the oxidation (of carbon) and reduction state change (oxygen).

Now in a actual redox reaction, when the atoms split up the electronegative atoms pull their electrons with them when they leave. In this case, the atom that lost the electron was oxidized and the one that gained it was reduced.

I am sure you can see how you cannot have oxidation (the loss of electrons) without a reduction of something else (the gain in electrons). Because charge neutrality must be maintained. Redox reactions allow for a controlled shuttling of electrons between species. In biochemistry these reactions are the equivalent of wires. its a means for electrons to flow.

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