For a galvanic cell that uses the following two half-reactions,
Cr₂O₇^2-(aq) + 14 H⁺(aq) + 6 e^- → 2 Cr³⁺(aq) + 7 H₂O(l)
Pb(s) → Pb²⁺(aq) + 2 e^-
How many moles of Pb(s) are oxidized by three moles of Cr₂O₇^2-(aq) ?

Question

Quizplus · Accepted Answer

Each mole of Cr2O7^2- requires 6 electrons, so 3 moles require 18 electrons. Since each mole of Pb provides 2 electrons, 9 moles of Pb are needed to provide 18 electrons.

For a Galvanic Cell That Uses the Following Two Half-Reactions