SA 150 Lecture 9: 21-5A_NotesExam
SchoolSimon Fraser University
DepartmentSociology and Anthropology
Course CodeSA 150
ProfessorAmie Mc Lean
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21-5A. Electrochemical Cell – Qualitative
Electrons are exchanged between two connected half-reactions.
Movement of electrons is electricity.
Generate electricity thru Chemistry!
a) Example How can we harness the electricity from the following redox reaction?
2Ag+ + Cu (s)
2Ag (s) + Cu+2
K+ NO3-- →
Ag (s) NO3- (filled with electrolyte) Cu+2 Cu (s)
AgNO3 (aq) C u(NO3)2 (aq)
Ag+ + e- → Ag (s) Cu (s) → Cu+2 + 2e-
Positive Terminal Negative Terminal
(becomes negative- (becomes positive-
Electrons flow into it and Electrons flow out of it and
Positive ions disappear) Positive ions appear)
1. Cu (s) will spontaneously oxidize to a small extent to start the process.
2. e- left behind by the oxidation of Cu (s) travel though wire as an electrical
current to the cathode, where they are picked up by the Ag+ ions.
3. The Ag+ ions are then reduced to Ag (s), which is deposited on the cathode.
4. In order for e- to continue flowing, the cell must be overall electrically
5. To prevent a build up of Cu+2 is right half cell and NO3- in left half cell, the
salt bridge allows them to “escape”
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