Finding the oxidized and reduced element

  • Thread starter Thread starter physics=world
  • Start date Start date
  • Tags Tags
    Element
Click For Summary

Discussion Overview

The discussion centers around identifying the oxidized and reduced elements in the chemical reaction CO2 + C = 2CO. Participants explore how to determine oxidation states and the changes that occur during the reaction.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses uncertainty about identifying oxidized and reduced elements in the reaction CO2 + C = 2CO.
  • Another participant suggests calculating oxidation numbers for all atoms present in the equation.
  • A participant proposes oxidation numbers for carbon and oxygen in both reactants and products, indicating C=+4 and O=+2 for CO2, and C=+2 for CO in the products.
  • There is a discussion about which atoms' oxidation numbers changed during the reaction.
  • One participant concludes that carbon is being reduced based on their calculations.
  • Another participant challenges the conclusion, stating that reduction cannot occur without oxidation and asks what is being oxidized.
  • Oxygen is initially suggested to be oxidized, but a participant corrects the oxidation number for oxygen, stating it remains -2 in all compounds.
  • Participants discuss that there are two different carbon atoms in the reaction, with one being oxidized and the other reduced.
  • Disproportionation is introduced as a concept where identical atoms can be both oxidized and reduced simultaneously.
  • Clarification is provided that one carbon atom goes from +4 to +2 (reduced) and the other from 0 to +2 (oxidized).

Areas of Agreement / Disagreement

Participants generally agree that carbon is involved in both oxidation and reduction processes, but there is disagreement regarding the oxidation states of oxygen and the identification of which specific carbon is oxidized or reduced.

Contextual Notes

There are unresolved aspects regarding the correct assignment of oxidation numbers, particularly for oxygen, and the implications of disproportionation in similar reactions.

physics=world
Messages
109
Reaction score
0
1. I need to find the element being oxidized and reduced for:

CO2 + C = 2CO

I don't know how to do it for this one.





3. I know how to do it for ones like this:

2Al + 3Cl2 = 2Al(3+) 6Cl(-)

it would be

zero for elemental Al and Cl

and the oxidation number for the product would be its charge.

but how do I do it for ones like this.

CO2 + C = 2CO
 
Physics news on Phys.org
Have you tried to calculate oxidation numbers for all atoms present in the equation?
 
Would it be

for the left side:

C=+4, O =+2 for CO2

and elemental C = 0

and for the right side:

C=+2, O =+2 for 2CO
 
So far, so good. Which atoms oxidation numbers changed?
 
If I add the C atom and subtract from the other side would this be correct:

(4+0) - 2 = 2

So, C would be reduced.
 
I am not sure what you are doing, but your conclusion is partially right. Carbon is being reduced, but you can't have reduction without oxidation.

What is being oxidized?

Hint: I was referring to atoms (not elements) for a purpose.
 
Oxygen is being oxidized, but how much is the oxidation number increased by?
 
No, oxygen oxidation number doesn't change - it was -2 before and it is -2 after.

Sigh, I just realized you calculated oxidation numbers for oxygen wrong - you wrote them as +2. No, it was -2 in all compounds.
 
yes I noticed that as well
 
  • #10
So, what is being oxidized?
 
  • #11
carbon
 
  • #12
Yep. You have two different carbon atoms on the left - one is getting oxidized, the other is getting reduced.

Sometimes it can get even more surprising, when you have two identical atoms on the left and they get reduced and oxidized at the same time - it is called disproportionation. The simplest example is probably

Cl2 + 2OH- → Cl- + OCl- + H2O

(try to assign oxidation numbers and see what is happening here).
 
  • #13
that is surprising. I did not know about that.

So, is the other C going from 0 to 2?
 
  • #14
Yes, one C is going from +4 to +2, the other one from 0 to +2. First is reduced, the other is oxidized.
 

Similar threads

Replies
5
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 6 ·
Replies
6
Views
5K
Replies
6
Views
9K
Replies
7
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 11 ·
Replies
11
Views
9K