Solve Selective Reduction of Sn4+ to Sn2+ w/o Sn2+ to Sn

  • Thread starter Thread starter higherme
  • Start date Start date
  • Tags Tags
    Reduction
Click For Summary

Discussion Overview

The discussion revolves around the selective reduction of Sn4+ to Sn2+ in a galvanic cell context, specifically exploring which anodic half-reactions would allow for this reduction without facilitating the further reduction of Sn2+ to Sn. Participants analyze standard reduction potentials and the conditions for spontaneity in electrochemical reactions.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant presents the standard reduction potential for Sn4+ to Sn2+ as +0.15V and lists several anodic half-reactions to evaluate their spontaneity.
  • Calculations of oxidation potentials for various reactions are shared, with specific values provided for each half-reaction.
  • It is noted that for a spontaneous reaction, the Ecell must be positive, and some reactions are identified as yielding a positive Ecell for the reduction of Sn4+ to Sn2+ while preventing the reduction of Sn2+ to Sn.
  • A question is raised about whether an Ecell of zero, indicating equilibrium, can be considered spontaneous.
  • Another participant expresses uncertainty about their approach and seeks confirmation on their calculations.
  • There is a side conversation about a related question involving selective oxidation instead of reduction.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the definition of spontaneity when Ecell equals zero. There is no consensus on the correct approach or final answers, and multiple viewpoints on the calculations and interpretations of spontaneity are present.

Contextual Notes

Participants reference standard reduction potentials from a table, but specific assumptions or definitions related to spontaneity and equilibrium are not fully clarified. The discussion includes various half-reactions and their potentials, which may depend on specific conditions not detailed in the posts.

higherme
Messages
126
Reaction score
0

Homework Statement



Given: Sn4+ + 2e- --->Sn2+ Estandard=+0.15V
For a galvanic cell under standard condition, which of the following anodic half reaction would produce at the cathode a spontaneous reduction of Sn4+ to Sn2+ but NOT Sn2+ to Sn.

Pb --> Pb2+ + 2e-
Sn2+ --> Sn4+ + 2e-
Pb + SO42- --> PbSO4 + 2e-
Sn --> Sn2+ + 2e-
Fe --> Fe3+ + 3e-
Ni --> Ni2+ + 2e-

The Attempt at a Solution



I found the oxidation potential for all of the above reactions:

+0.126
-0.139
+0.355
+0.141
+0.036
+0.236, respectively

For a spontaneous reaction, the Ecell has to be positive. I calculated the Ecell for each of those reactions with Sn4+ + 2e- --->Sn2+ Estandard=+0.15V and with Sn2+ + 2e---->Sn

I found that Pb --> Pb2+ + 2e-, Sn2+ --> Sn4+ + 2e-, and Fe --> Fe3+ + 3e- are the only three that produce a Ecell that is positive for Sn4+ to Sn2+ and NOT Sn2+ to Sn

but for Sn --> Sn2+ + 2e- reacting with Sn2+ + 2e---->Sn, the Ecell is obviously equation to zero, would that considered to be spontaneous??

can someone check if I am doing this right?

Thanks a lot =)
 
Physics news on Phys.org
am I on the right track here?
 
do u go to the UoW? :)
 
what is "UoW"?
 
lol i guess not


by the way in ur questions do u have one like this..

Selective Oxidation (not reduction)

--------------------------------------------------------------------------------

1. The standard reduction potential for the half-reaction

Sn4+ + 2e- Sn2+
is +0.15 V.
Consider data from the table of standard reduction potentials for common half-reactions, in your text.

For a galvanic cell under standard conditions, which of the following cathodic half reactions would produce, at the anode, a spontaneous oxidation of Sn to Sn2+ but not Sn2+ to Sn4+.

Sn2+ + 2e- Sn
Pb2+ + 2e- Pb
2H2O + 2e- H2 + 2OH-
PbSO4 + 2e- Pb + SO42-
Fe2+ + 2e- Fe
Fe3+ + 3e- Fe
 
yeah, something similar to that.
 
can someone please check what I'm doing wrong here... I'm still not getting the correct answer =(
 
if the Ecell = 0 (in equilibrium) is that still considered to be spontaneous?
 

Similar threads

Solving Selective Oxidation with Standard Reduction Potential
  • · Replies 6 ·
Replies
6
Views
9K