Circle the correct reaction What is the E potential for the reaction you have ch
ID: 996245 • Letter: C
Question
Circle the correct reaction What is the E potential for the reaction you have chosen. Use the standard reduction potentials to determine the net reaction and st contains a 1.00 M solution of the indicated cation in contact with an electrode 9. andard cell potential for the cell below. Each cell of that neutral metal. Electron Flow Standard Reduction Potential (E) Fe2+ + 2e- Fe Cr3- + 3e- Cr -0.447 V Fe -0.744 V Cr 2+ Fe 2- SO 2- SO Separator interface Reaction: (A) (B) 2 Cr + 3 Fe 2Cr3-+ 3 Fe 2 Cr3++ 3 Fe2. 2 Cr+ 3 Fe2+ i) Circle the correct net reaction from the choices above. i) What is the E (potential) for the reaction you have chosen?
Explanation / Answer
The standard reduction potentials are :
Fe2+ + 2e- ------> Fe ; E' = -0.447 V ----(1)
Cr3+ + 3e- ------> Cr ; E' = -0.744 V ----(2)
Since the reduction potential of Cr system is less it undergoes oxidation at anode & Fe undergoes reduction at cathode.
The overall reaction is obtained by combining these two equations so that the charge should balance each other.
This cab be done as follows: (3xEqn(1) ) + ( 2xEqn(2) we get
3Fe2+ + 6e- + 2Cr3+ + 6e- ------> 2Cr + 3Fe
The cell reaction is 2Cr + 3Fe2+ ------> 3Fe + 2Cr3+
This is the net reaction
Therefore option (C) is correct
So standard potential of the cell , Eo = Eocathode - Eoanode
= EoFe2+/Fe - EoCr3+/Cr
= -0.447 -(-0.744)V
= 0.297 V
Therefore the Eo of the cell is +0.297V