How to choose a reduced or oxidated form in a redox

  • Thread starter Peppe
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Hi guys i'm studying about general chemistry in a physics class.
I've some exercices that i'm unable to solve, stuff like this:


Copper can be solubilizated in water, oxidating in Cu++ form, reacting with HCrO4- in an acid enviroment realized by H2SO4. Write down the balanced reaction.


my problem is to write (not to balance) an reduction/oxidation reaction.


The copper is oxidating, so cromium or hydrogen have to reduce. I've thought about 3 different reaction.
So, in my proposal, the unbalanced reaction are:

Cu + HCrO4- -> Cu++ + Cr2O3 + H2O
Cu + HCrO4- -> Cu++ + CrO + H2O
Cu + HCrO4- -> CuCrO4 + H2

how to choose the correct one?
ciao!
 

Answers and Replies

  • #2
Borek
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Cr usually gets reduced to Cr3+ in such situations. You are probably right about copper chromate precipitation.

Please note: copper is not "oxidating", copper is "being oxidized" while chromium is being reduced.
 
  • #3
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Thanks for the reply :) :) .

But how can i learn what usually a species does? :O
 

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