• Support PF! Buy your school textbooks, materials and every day products Here!

Selective Reduction

  • Thread starter higherme
  • Start date
  • #1
129
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 =)
 

Answers and Replies

  • #2
129
0
am I on the right track here?
 
  • #3
302
1
do u go to the UoW? :)
 
  • #4
129
0
what is "UoW"?
 
  • #5
302
1
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
 
  • #6
129
0
yeah, something similar to that.
 
  • #7
129
0
can someone please check what i'm doing wrong here... i'm still not getting the correct answer =(
 
  • #8
129
0
if the Ecell = 0 (in equilibrium) is that still considered to be spontaneous?
 

Related Threads on Selective Reduction

  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
0
Views
2K
  • Last Post
Replies
9
Views
2K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
7
Views
5K
  • Last Post
Replies
10
Views
20K
  • Last Post
Replies
6
Views
6K
  • Last Post
Replies
2
Views
5K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
1
Views
6K
Top