Chem- Conjugate Redox Pairs (1 Viewer)

[hs17]

Is there a specific order when naming/identifying these pairs? Do we have to put either the oxidant or reductant first?

 

[Velocifire]

Page 46 of the Holy Grail

 

[hs17]

I can't seem to find something exactly on the pairs?

 

[Velocifire]

What is this 9000IQ stuff I need to revamp the notes halp

 

[hs17]

Am I blind or is it not there?

 

[hs17]

It's not really a major thing but I was still curious if there's a rule to this or not

 

[hs17]

Nope it doesn't matter I don't think. Just make sure the product is on the product side, reactant on reactant side then just fill in where the electrons gained/ loss should be. Someone correct me if I'm wrong.

Yay thank you!

 

[jazz519]

Not really can write it any order for just stating a redox pair.

But that will change if they ask you to write something like cell notation, then we actually have a set notation:
Zn(s) | Zn2+(aq) || Pb2+(aq) | Pb(s)

For example with that left side is always the anode, right side is always the cathode. the | represent a state change and the || represents the salt bridge

 

[hs17]

Not really can write it any order for just stating a redox pair.

But that will change if they ask you to write something like cell notation, then we actually have a set notation:
Zn(s) | Zn2+(aq) || Pb2+(aq) | Pb(s)

For example with that left side is always the anode, right side is always the cathode. the | represent a state change and the || represents the salt bridge

thank you!!!

 

[CM_Tutor]

I note that the thread title refers to "conjugate redox pairs"... note that conjugate pairs and redox pairs are not the same thing, and in fact a conjugate pair cannot also be a redox pair and vice versa.

You may not have yet met conjugate pairs, which are part of Lowry-Bronsted theory of acids and basis, but they don't involve redox changes. A common MC question is to give four pairs and to ask which is a conjugate pair, like:

(A) H₃O⁺ / OH^–

(B) SO₃ / HSO₃^–

(C) H₂PO₄^– / H₂PO₃^–

(D) HNO₂ / NO₂^–

 

[hs17]

This is what the textbook says...?

 

[hs17]

I note that the thread title refers to "conjugate redox pairs"... note that conjugate pairs and redox pairs are not the same thing, and in fact a conjugate pair cannot also be a redox pair and vice versa.

You may not have yet met conjugate pairs, which are part of Lowry-Bronsted theory of acids and basis, but they don't involve redox changes. A common MC question is to give four pairs and to ask which is a conjugate pair, like:

(A) H₃O⁺ / OH^–

(B) SO₃ / HSO₃^–

(C) H₂PO₄^– / H₂PO₃^–

(D) HNO₂ / NO₂^–

what would be the answer here? just curious

 

[Velocifire]

what would be the answer here? just curious

When In doubt, pick anything really

 

[hs17]

When In doubt, pick C

let's see...

 

[Velocifire]

A - Absolute Answer
B - Best Answer
C - Correct Answer
D - Definite Answer

Oop guess that’s debunked

 

[CM_Tutor]

what would be the answer here? just curious

The answer is D.

A gives two species that are conjugates of water, but are not conjugates of each other, which must differ by exactly one H⁺.

B has two species which differ by a proton and a pair of electrons - that is, by H^-

C has two species which differ by an O atom.

 

[CM_Tutor]

View attachment 28566
This is what the textbook says...?

It's not a terminology that I have seen used much, and it's not a terminology I would use because of the potential for confusion. It is also unhelpful in that there are multiple oxidation states and results possible in some cases. Cu²⁺ can be reduced to Cu⁺ or to Cu. Fe³⁺ can be reducecd to Fe²⁺ or to Fe. In organic chemistry, the oxidant MnO₄^- is reduced to Mn²⁺ in acidic media and to MnO₂ in basic conditions.

In acid/base theory, a conjugate pair is precisely defined - it consists of a species and the species it becomes during a Lowry-Bronsted acid/base reaction. Ammonia is a weak base and reacts in water according to:

NH₃ + H₂O ---> NH₄⁺ + OH^-

Ammonia has acted as a base and accepted a proton, forming its conjugate acid, yielding the conjugate pair NH₃ / NH₄⁺
Water has acted as an acid and donated a proton, forming its conjugate base, yielding the conjugate pair H₂O / OH^-

Whilst some substances (including water) can belong to two different conjugate pairs (the second being H₂O / H₃O⁺), there is still no doubt about which pair is present in a given system and what the possible conjugates of a species are. Unfortunately, the same cannot be said for the term "conjugate redox pair" as it is being defined here.

It is worth bearing in mind that textbooks can contain mistakes, as well as describe approaches that are more or less helpful than alternatives. If a teacher / textbook wants to adopt this approach, they are free to do so - but that doesn't make it unambiguous "truth."