Show all work to receive full or partial credit. PLEASE HELP! Balance the follow
ID: 581285 • Letter: S
Question
Show all work to receive full or partial credit. PLEASE HELP!
Balance the following redox reaction by the half-reaction method in acidic medium correctly. Show each step. (2 points)
S2O6^2-(aq) + IO3^-(aq) arrow SO4^2-(aq) + I^-(aq)
What is the cell potential at standard state for the redox reaction in problem 1? (1 point)
A Galvanic cell was constructed for this reaction. The pH of the solutions is 3.50. The temperature is 25oC. The concentration of the other species are:
[I^-] = 0.500M , [IO3^-]= 0.00750M , [S2O6^2-]= 1.25M , [SO4^2-]= 0.750M
What is the cell potential in volts of the Galvanic cell? (2 points)
Explanation / Answer
First, define the “ACIDIC” solution/conditions as H+ presence and
Basic solution implies OH- once it is balanced.
Also; note that ALL species must be balanced, as well as charges
Typical steps:
1) split half redox cells
S2O6-2 = SO4-2
IO3- = I-
2) balance atoms other than O,H
S2O6-2 = 2SO4-2
IO3- = I-
3) balance O by adding H2O
2H2O + S2O6-2 = 2SO4-2
IO3- = I- + 3H2O
4) balance H by adding H+
2H2O + S2O6-2 = 2SO4-2 + 4H+
6H+ + IO3- = I- + 3H2O
5) balance charge by adding e-
2H2O + S2O6-2 = 2SO4-2 + 4H+ + 2e-
6e- + 6H+ + IO3- = I- + 3H2O
6) balance e- by multiplying by the Greatest common divisor
6H2O + 3S2O6-2 = 6SO4-2 + 12H+ + 6e-
6e- + 6H+ + IO3- = I- + 3H2O
7) Add both equations
6e- + 6H+ + IO3- + 6H2O + 3S2O6-2 = 6SO4-2 + 12H+ + 6e-+ I- + 3H2O
8) simplify repeating elements, H+, H2O, and e- typically
IO3- + 3H2O + 3S2O6-2 = 6SO4-2 + 6H+ + I-
IO3- + 6H+ + 6e- --> I- + 3H2O E = 1.085
2SO4-2 + 4H+ + 2e- <-> S2O6-2 + H2O E = -0.22
b)
E°cell = Ered - Eox
E°cell = 1.085 - -0.22
E°cell = 1.305V
c)
IO3- + 3H2O + 3S2O6-2 = 6SO4-2 + 6H+ + I-
Q = [SO4-2]^6 * [H+]^6 * [I-] /([IO3-][S2O6-3]^3)
Q = (0.75^6)(10^-3.5)^6 * (0.5) /((0.0075)(1.25^3))
Q = 6.075*10^-21
n = 6 e-
E = E° - 0.0592/6*log(6.075*10^-21)
E = 1.305 + 0.1994
E = 1.5044V