Selenium Oxidation State in Redox Reaction

In summary, the conversation discusses a redox question involving the reaction between selenium oxide and chromium sulfate. Based on the given information, it is determined that selenium is reduced and chromium is oxidized. The oxidation state of selenium is converted from +4 to 0, while the oxidation state of chromium changes from +2 to +3. There is some uncertainty about the formation of selenium sulfate, but it is concluded that the reaction results in the formation of H2SO4.
  • #1
ShakeWell
7
0
Redox question:

12.53 ml of .05093 M selenium oxide (SeO2) reacted exactly with 25.52 ml of .1 M CrSO4. Cr+3 is formed. To what oxidation state is Selenium converted?

I think that the ml + M stuff gives you the ratio between moles of SeO2 and moles of CrSO4 (1m SeO2 = 4m CrSO4). But how am I supposed to figure out what happens to the Se?
 
Chemistry news on Phys.org
  • #2
Okay, this is how I'm looking at it, based solely on the information alone and not by looking up the oxidation states of selenium. I don't know if it's right but...
Ratio is 1:4, we know that, and we also know that chromium goes from +2 to +3. So SeO2 needed 4 moles of CrSO4 and so it follows that it needed 4 moles of e- from the Cr+2. So one SeO2 receives 4 e-'s and makes the reduction: Se(+4) + 4e- --> Se(0) which is the selenium metal.

Wow it looks so nice, we've solved the problem, and I don't know if it's right. Something came up though, when you write out the equation there's a problem with the sulfate ion floating around:

SeO2 + CrSO4 --> Se + Cr2O3 + SO4(-2)

so maybe it reacts with the water in the solution (assuming everything's aqueous and it probably is), and forms H2SO4.

2H+ + SeO2 + 4CrSO4 --> Se + 2Cr2O3 + H2SO4

I don't think this is right, so can someone please help.
 
  • #3
someone care to help? I'm sorry but I just really want to know the answer, it bugs me when I can't solve a problem.
 
  • #4
I'm thinking its 2+, that is it has been reduced while the chromium has been oxidized. Nonmetalic elements usually have oxidation states at even intervals e.g. from 4+ to 2+. Tis an oxidation reduction reaction.
 
  • #5
Se has oxidation states of +6, 4, 1, and -2. +1 being very rare. http://www.ivstandards.net/extras/pertable/
Regardless though, based on the information that was given and my reasoning, was it a correct approach?
And selenium sulfate doesn't exist, I can't find it on chemfinder, so I don't think that that will even form. SO what the hell is going on...
 
  • #6
Chromium is oxidized, which means it has lost some electrons. Therefore it is a reducing agent; something has been reduced. Selenium is reduced. If the original assumption was right-1 Se for every 4 Cr, than we can assume that 4 electrons are lost for every 1 Se. Assuming that the original oxidation state of Se was 4+ we can say that the oxidation state for Se is now 0. However, I am not completely sure about this. I'll check back later with other details, I am a bit busy right now.
 
  • #7
Yeah, the above is correct.
 
  • #8
thanks.
what happens to SO4(2-)?
 

1. What is the oxidation state of Selenium in a redox reaction?

In a redox reaction, the oxidation state of Selenium can vary depending on the other elements involved. However, the most common oxidation states are +4 and +6.

2. How does the oxidation state of Selenium change in a redox reaction?

Selenium can either be oxidized or reduced in a redox reaction. When it is oxidized, its oxidation state increases, and when it is reduced, its oxidation state decreases. This change in oxidation state is due to the transfer of electrons.

3. What factors influence the oxidation state of Selenium in a redox reaction?

The oxidation state of Selenium can be influenced by the electronegativity of the other elements involved in the reaction, as well as the overall charge of the compound. Additionally, the presence of certain ions or molecules can also affect the oxidation state of Selenium.

4. Can the oxidation state of Selenium be predicted in a redox reaction?

It is not always possible to predict the exact oxidation state of Selenium in a redox reaction, as it can vary depending on the specific conditions and reactants involved. However, knowing the general trends and rules for assigning oxidation states can help in making an educated prediction.

5. How is the oxidation state of Selenium determined in a redox reaction?

The oxidation state of Selenium can be determined by balancing the overall charge of the compound and using the oxidation state rules. In some cases, it may also be necessary to use experimental methods such as redox titration to accurately determine the oxidation state.

Similar threads

Electron transfer and oxidation state
    • Chemistry
Replies
11
Views
2K
Oxidation using selenium dioxide
    • Chemistry
Replies
5
Views
21K
Oxidation Number: Understand, Rules & Balance Redox Reactions
    • Chemistry
Replies
2
Views
2K
Understanding Redox Reactions: A Beginner's Guide
    • Chemistry
Replies
4
Views
3K
Chemistry redox reaction - gases mixing
    • Biology and Chemistry Homework Help
Replies
5
Views
4K
Solved: Redox, Catalyzed Decomposition Reaction
    • Chemistry
Replies
8
Views
2K
Diffusion -- Tarnishing of metal surfaces
    • Engineering and Comp Sci Homework Help
Replies
2
Views
3K
Atom-Transfer Radical Polymerization: Method Question
    • Chemistry
Replies
3
Views
2K
What is the oxidation state of Cr in Cr(CO)6
    • Chemistry
Replies
5
Views
8K
Combustion Reactions: C5H12 + O2 - Steps & Oxidation States
    • Biology and Chemistry Homework Help
Replies
6
Views
2K

Hot Threads

Recent Insights

Back
Top