Consider the following unbalanced redox reaction which is being used to run a vo
ID: 943797 • Letter: C
Question
Consider the following unbalanced redox reaction which is being used to run a voltaic cell: Cr_(s)+ Fe^2+_(aq) rightarrow Cr^3+_(aq) + Fe_(s) Write the balanced oxidation half-reaction for this cell. Write the balanced reduction half-reaction for this cell. Write a balanced chemical equation that describes the overall cell reaction. Assuming that the cell is operating at standard conditions, what would be the potential of the cell in volts? If [Ct^3+] = 0.00010 M and [Fe^2+] = 2.0 M, what would be the potential of the cell in volts at 25 degree C?Explanation / Answer
a. Oxidation half-reaction : Cr(s) ---> Cr3+(aq) + 3e-
b. Reduction half reaction : Fe2+(aq) + 2e- ---> Fe(s)
c. Overall cell reaction : 2Cr(s) + 3Fe2+(aq) ---> 2Cr3+(aq) + 3Fe(s)
d. Cell potential = Eo = -0.44 - (-0.74) = 0.30 V
e. Using Nernst equation,
E = Eo - 0.0592/6 log([Cr3+]^2/[Fe2+]^3)
= 0.3 - 0.0592/6 log((0.0001)^2/(2)^3)
= 0.39 V (or 0.4 V)