Chemistry Flashcards
What is an electrolytic cell?
Converts electrical → chemical energy via non-spontaneous redox
Anode reaction in CuCl₂ electrolysis?
2Cl⁻ → Cl₂ + 2e⁻
Cathode reaction in CuCl₂ electrolysis?
Cu²⁺ + 2e⁻ → Cu
Total EMF for CuCl₂ cell?
-1.02V
Front
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What’s the key difference between galvanic and electrolytic cells?
Galvanic: spontaneous (ΔG<0), Electrolytic: non-spontaneous (ΔG>0, needs external power)
Why must electrolytic cells use an external battery?
To provide the activation energy for non-spontaneous redox
Standard notation for electrolytic cell diagrams
Battery symbol on the left, anode (+) on the left
Anode material in CuCl₂ electrolysis?
Graphite/Pt (inert)
Oxidation half-reaction at anode in CuCl₂
2Cl⁻ → Cl₂(g) + 2e⁻
Why does Cl₂ gas form at anode instead of O₂?
Cl⁻ has lower oxidation potential (-1.36V) vs water (-1.23V)
Cathode material in CuCl₂ electrolysis?
Graphite/Pt (inert)
Reduction half-reaction at cathode
Cu²⁺ + 2e⁻ → Cu(s)
Calculate total EMF for CuCl₂ electrolysis
E°cell = E°cathode - E°anode = 0.34V - 1.36V = -1.02V
Minimum external voltage required for CuCl₂ electrolysis?
> 1.02V (must overcome negative EMF)
What happens if voltage < |1.02V|?
No reaction occurs
Why use inert electrodes?
Prevent electrode from participating in reactions
What happens if you use Cu electrodes?
Anode dissolves (Cu → Cu²⁺ + 2e⁻) instead of Cl⁻ oxidizing
Industrial use of electrolytic cells
Electroplating, aluminum extraction, chlorine production
Direction of electron flow
Battery (-) → Cathode → Solution → Anode → Battery (+)
Direction of ion migration
Anions → Anode, Cations → Cathode
Color change observed at cathode in CuCl₂ electrolysis?
Blue [Cu²⁺(aq)] fades as Cu deposits
Gas test for anode product in CuCl₂ electrolysis?
Damp litmus paper → Bleaches (Cl₂ gas)
Mass change at anode in CuCl₂ with inert electrodes?
No change (graphite/Pt doesn’t dissolve)
