The Nernst Equation Video Lessons

Concept:

# Problem: The cell diagram for the lead-acid cell that is used in automobile and truck batteries isPb(s) l PbSO4 (s) l H2SO4 (aq) l PbO2(s), PbSO4(s) l Pb (s)where the comma between PbO2 (s) and PbSO4 (s) denotes a heterogeneous mixture of the two solids and the right-hand lead electrode is nonreactive.a) Write a balanced equation for the net cell reaction:b) Look up standard potentials for the oxidation and the reduction reactions, then calculate the value of E°cell.c) Calculate the value of ΔG°rxnd) Calculate the value of Ecell at 25°C is [H2SO4] = 10.0Me) How many lead-acid cells are in a 12 V car battery? Round to the nearest integer.

###### FREE Expert Solution

Part a: To write the balanced equation for the net cell reaction:

Pb(s) l PbSO4 (s) l H2SO4 (aq) l PbO2(s)PbSO4 (s) l Pb (s)

(non reactive)

Step 1: Identify cathode and anode from E°(refer to textbooks/online)

PbO2(s) + SO42-(aq) + 4 H+(aq) + 2e- → PbSO4(s) + 2 H2O(l)      E° = 1.69 V

PbSO4(s)  + 2 e→  Pb(s) + SO42-(aq)                                                E° = -0.36 V

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###### Problem Details

The cell diagram for the lead-acid cell that is used in automobile and truck batteries is

Pb(s) l PbSO4 (s) l H2SO4 (aq) l PbO2(s), PbSO4(s) l Pb (s)

where the comma between PbO2 (s) and PbSO4 (s) denotes a heterogeneous mixture of the two solids and the right-hand lead electrode is nonreactive.

a) Write a balanced equation for the net cell reaction:

b) Look up standard potentials for the oxidation and the reduction reactions, then calculate the value of E°cell.

c) Calculate the value of ΔG°rxn

d) Calculate the value of Ecell at 25°C is [H2SO4] = 10.0M

e) How many lead-acid cells are in a 12 V car battery? Round to the nearest integer.