Hey everyone, couldn't find the answer I'm looking for online anywhere. I'm a little clueless when it comes to chemistry, sorry for the rookie question.
For conjugate redox pairs, I'm having some trouble identifying how much of a substance to include in my answer. All of these examples are from Chapter Review 4 of Heinemann, Q13.
1) Fe + I2 -> FeI2
The textbook answers say the redox pairs are Fe/Fe3+ and I2/I-. I'm guessing this is because it wouldn't be specific enough if you just gave the whole compound, FeI2, since the compound is involved in both oxidation and reduction.
2) Mg + FeCl2 -> MgCl2 + Fe
Conjugate redox pairs are Mg/Mg2+ and Fe2+ and Fe. Why isn't it listed as FeCl2 and MgCl2?
3) 10Br- + 2MnO4- + 16H+ -> 2Mn2+ + 8H2O + 5Br
Textbook answer says the reduction conjugate redox pair is MnO4-/Mn2+. So does that mean that for polyatomic ions, the whole thing is included in the answer?
4) Cu + 2NO3- + 4H+ -> Cu2+ + 2NO2 + 2H2O
For this one, the reduction conjugate redox pair is NO3- and NO2. Why is it NO2 rather than just N4+?
I guess I get equation 1, but to me it seems like 2 and 4 contradict themselves. Is there a particular trend based on what type of compound it is (ionic compound vs covalent compound) or is it just random and doesn't matter. Hopefully I was clear enough!