Overall reaction: Pb(s) + PbO2(s) + 2 H+(aq) + 2 HSO4-(aq) -> 2 PbSO4(s) + 2 H2O(l) Cathode half-cel — Electrochemistry Chemistry Question
Problem Context
Overall reaction: Pb(s) + PbO2(s) + 2 H+(aq) + 2 HSO4-(aq) → 2 PbSO4(s) + 2 H2O(l)
Cathode half-cell reaction: PbO2(s) + 3 H+(aq) + HSO4-(aq) + 2 e- → PbSO4(s) + 2 H2O(l)
- The equations above represent reactions associated with the operation of a lead storage battery. The first is the overall reaction that occurs as the battery produces an electrical current, and the second is the half-reaction that occurs at the cathode.
a.1 pt
Model Answer
+6
1 point is earned for the correct answer.
b.1 pt
Model Answer
Pb(s) + HSO4-(aq) → PbSO4(s) + H+(aq) + 2 e-
1 point is earned for a correct equation.
c.2 pts
Model Answer
100. g Pb x (1 mol Pb / 207.2 g) = 0.483 mol Pb
0.483 mol Pb x (2 mol e- / 1 mol Pb) = 0.966 mol e-
0.966 mol e- x (96,485 C / 1 mol e-) = 93,200 C
I = q / t ⇒ t = q / I
t = 93,200 C / 5.00 amp = 18,600 s
1 point is earned for the correct number of moles of electrons (may be implicit).
1 point is earned for the correct time based on the moles of electrons.
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