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Just cant grasp the concept of redox rxns

  1. Jan 25, 2009 #1
    I have read about 20 explanations and tutorials and heard people talk about reducing and oxidizing compounds countless times but the concept continues to elude me. I know that oxidizing has 3 meanings but in this case it refers to one compound taking electrons off another compound and reduction is the opposite.

    I understand that much but these terms are used generically and I hear people say "reduce compound A" or "oxidize compound B" but when I look at the reaction it makes no sense to me. People always talk about a certain compound being a good oxidizer for another compound.

    What is the purpose of oxidizing a compound? Is it just to break a certain chemical bond to allow another chemical reaction to occur and a new compound to be formed?

    That question probably has no simple answer but what I'm asking is why these 2 reactions (oxidation or reduction) are talked about so ambiguously everywhere
  2. jcsd
  3. Jan 25, 2009 #2
    Well it all started with metal oxides. You had an oxide of one metal A as a donor and another metal B as an acceptor. When the mixture was heated up, the mixture burned and all the oxygen would move from metal A to metal B. In the end you were left with pure metal A and B as an oxide. Thus A was reduced and B was oxidized --> red-ox. This was nice for technical applications, because the oxidation of B would produce all the energy needed to reduce A.
    Thermite for example is used to produce liquid iron to weld railroad tracks, which is much nicer than heating up pure iron with a torch until it melts.

    Today one focuses on the bindings. Oxygen has two electrons that can form bindings. Any other compound that has such an electron pair can replace oxygen and the reaction is still called a redox reaction.

    As far as I see it: you have one "oxide" that you want to remove the "oxygen" from, so you take something that is easy to get and that likes the "oxygen" more, and this will also provide you with the energy that you need for the reduction. Replace "oxygen" with sulfur or what you like.
  4. Feb 1, 2009 #3
    Ah right now I get it thanks a lot. That was a nice visual explanation. I find that some chemistry tutorials and books explain things way too abstractly in just words and expect people to grasp the concepts but in my case at least I have to visualize a concept before I can fully grasp it. Yea I memorize the rules and all that crap but its only when I make an animated mental diagram of whats going on that I can safely say I understand the concept.

    In the future when Ive gained a vast knowledge of chemistry I'm going to write a highly visual chemistry basics book with examples of real life examples and all that.
  5. Feb 1, 2009 #4
    I started reading up on various organic reductions but I realized I still don't get the concept. Alright so one broad definition is that reducing a compound reduces its oxidation number.

    I'll use electroplating as an example. Lets say I want to electroplate a copper bar with gold. I negatively charge the copper bar so its oxidation number is say -50. I dump some Gold chloride in the solution and the positively charged Gold ions bond superficially bond to the copper bar raising its overall oxidation number. In this case did copper bar reduce the gold chloride or what the hell happened?
  6. Feb 1, 2009 #5


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    ManmanMurray, have you started studying oxidation-reduction reactions formally yet in a chemistry course?

    If you are still confused, think about the situation this way:
    If you hook an electric direct current power source to a liquid solution AND if the solution contains electrolytes (usually ionic compounds dissolved), then current can flow. (and if no electrolytes are present, then current flow is very very difficult). If a metal ion is present in the solution and if the voltage is at the right level, then this metal ion can move toward the cathode(where electrons may be trying to come through to the solution), and upon the metal ion reaching the cathode, it can gain one or more electrons at the cathode thereby becoming reduced as the solid metal and deposit on the cathode. Further, note carefully that an oxidation reaction is occurring at the anode. This has been a somewhat oversimplified description.
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