AAMC 5 Chem #24: Oxidation/Reduction

[LuminousTruth]

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When a strip of Cu is placed into H2O, no change is observed. However, when a strip of Cu is placed into a solution of HNO3, a gas evolves. What is the gas?

NO
H2

The explanation said when Cu reacts, Cu gets oxidized so something else must be reduced. And that NO was more likely to be reduced than H2. That makes sense - but is there another way to solve, like some way that is systematic that applies to every situation? (Like setting up a equation, solve for x, etc)

 

[1032]

i believe you are asking if there is a systematic way of determining if H2 or NO would be produced? if so, I feel that the explanation was pretty good about it. When given this question, I assumed it would be NO rather than H2 forming, because HNO3 is the oxidizing agent. So in this case, the oxidizing agent will be gaining electrons, and electronegativity always tells you that the more electronegative atom will pull on the electrons stronger, and so in all cases, the more electronegative specie will be reduced. I don't think there really is any sort of equations, because this is based on reasoning and understanding.