$\ce{Ag2O + H2O2 -> 2Ag + H2O + O2}$ My book says the medium is alkaline as $\ce{H2O2}$ gives $\ce{O2}$ on reduction only in alkaline medium only but $\ce{O2}$ is produced in acidic medium too. Is there really a way of recognizing the medium by looking at reaction equations??


Is there really a way of recognizing the medium by looking at reaction equations??

Yes and no...

For the particular reaction, you have to know some chemistry. In acid solutions hydrogen peroxide acts as an oxidizing agent: $$\ce{H2O2 + 2H^+ +2e^- -> 2H2O}$$

In neutral and basic solutions hydrogen peroxide acts as an reducing agent: $$\ce{H2O2 -> 2H^+ +2e^- + O2(g)}$$

The silver oxide is being reduced so the hydrogen peroxide must be acting as a reducing agent.

The real answer is that the balanced reaction isn't really enough information to duplicate the reaction. What temperature? How long for the reaction to take place? Since reaction would use excess hydrogen peroxide, how much was in excess and so on...

PS - Sometimes you have to consult the oracle to know the laboratory conditions. I asked Carnac the magnificent for more information.

enter image description here

This reaction was done by a red-headed girl. She was wearing a white lab coat over a red blouse and a blue skirt. She did have safety glasses which is a really sexy look over her hazel eyes in the chem lab. She was also wearing white leather sneakers.

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    $\begingroup$ My book say h2o2 can act as reducing and oxidising agent in both alkaline and acidic media. $\endgroup$ – jatin Mar 15 '16 at 10:21
  • $\begingroup$ Silver oxide is being reduced. So the hydrogen peroxide must be the reducing agent. In order to reduce hydrogen peroxide in acid you need to use a strong oxidizing agent which can't be silver oxide since it is already oxidized. $\endgroup$ – MaxW Mar 15 '16 at 14:53
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    $\begingroup$ Now it's getting clearer. Here's how I should analyze. I look at the equation, see that h2o2 is reducing agent. As h2o2 would like to act as reducing agent in alkaline medium or in acidic medium if it's reacting with a more powerful oxidizing agent, but ag2o isn't a powerful oxidizing group h2o2 must be in an alkaline medium. Wow. Great reasoning. But can you suggest how would I analyze if h2o2 is the oxidizing agent. I just can't think anymore, my brain is overheated right now. $\endgroup$ – jatin Mar 15 '16 at 20:13
  • $\begingroup$ If you were using the reaction in a publication then you'd explicitly specify all the reaction conditions so that a subsequent researcher could duplicate your work. So for example the time, temperature and pH for the reaction would be given in text not just the overall balanced reaction. Real science is about leaving footprints, not creating puzzles - like teachers do to test students... ;-) $\endgroup$ – MaxW Mar 15 '16 at 20:33
  • $\begingroup$ Yup. I think I was going in too much detail. Time to stop. $\endgroup$ – jatin Mar 15 '16 at 20:51

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