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Electrochemistry Galvanic Cells

Two half reactions that join electrically measuring voltage relationship between temp and cell voltage calculating thermodynamic functions.

1. Consider the cell consisting ofthe Fe3+(lM)/ Fe2+and and Br2(latm)/ Br-(lM) redox couples.

a. Write the reduction half-reaction and the corresponding standard reduction potential and
indicate which electrode does this occur at. .

b. Write the oxidation half reaction and the corresponding oxidation potential indicate which
electrode does this occur at. ...

c. Write the equation of the overall cell reaction and the value of EOcell?

2. Determine the cell voltage. EOcell. of a galvanic cell consisting of Sn+2(lM) / Sn and Cr+3 (lM)/ Cr redox couples.

3. Use the Nemst Equation to determine the cell potential. Ecell. of the galvanic cell consisting of Sn+2(O.OOOlM)ISn and Cr+3 (O.lM)/Cr redox couples.

4. State the purpose of the salt bridge in the experiment?

5. What is the sign of the anode in a galvanic cell? at the cathode?


Solution Preview

Br2 + 2 e-  2 Br-
Eo = 1.07 V
Occurs at cathode

Explanation: note that all galvanic cells have a positive overall potential (after addition the potential for the reduction half reaction and the potential for the oxidation half reaction). In order to have a positive overall potential, we ALWAYS want the more positive half reaction to be the reduction half reaction, that is, Br2 + 2 e-  2 Br-. In all types of cells, the reduction always occurs at the cathode.

Fe2+  Fe3+ + e-
Eo = - 0.77 V
Occurs at anode

Explanation: always remember to flip the equation for the oxidation half reaction in order to have the electron(s) ...

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