Electrochemistry
Track electron transfer, identify electrodes and agents, calculate cell potential, and interpret galvanic cells, electrolysis, plating, and corrosion.
Electrochemistry
Not yet verified on this browser.
Electrons leave the anode and arrive at the cathode
Oxidation is loss of electrons; reduction is gain of electrons.
AN OX: oxidation at the anodeRED CAT: reduction at the cathodeelectron flow: anode → cathodeThese electrode reactions are always true. What changes between galvanic and electrolytic cells is the electrode sign and the direction of energy conversion.
Galvanic cell
A spontaneous redox reaction produces electrical energy; anode is negative and cathode is positive.
Electrolytic cell
Electrical energy drives a nonspontaneous change; anode is positive and cathode is negative.
Salt bridge carries ions
Electrons travel through the wire; ions migrate through the electrolyte and bridge.
Oxidizing agent is reduced
It accepts electrons from the species it oxidizes.
Cell potential
Using reduction potentials: E°cell = E°cathode−E°anode.
Use AN OX → wire → RED CAT
Write the oxidation half-reaction at the left and the reduction half-reaction at the right:
ANODE: atoms lose e⁻ → e⁻ flow → CATHODE: ions gain e⁻Then check mass: a reactive metal anode often dissolves, while metal ions can plate onto the cathode.
Why it works
This single map prevents the most common mix-ups involving electrode names, electron direction, and which species gains or loses mass.
Five forms you should recognize
Problem: In Zn|Zn²⁺ || Cu²⁺|Cu, identify oxidation, reduction, and electron direction.
anode: Zn→Zn²⁺+2e⁻cathode: Cu²⁺+2e⁻→CuElectrons travel from the zinc electrode to the copper electrode.
Problem: E°red(Cu²⁺/Cu) = +0.34 V and E°red(Zn²⁺/Zn) = −0.76 V.
E°cell = 0.34−(−0.76) = +1.10 VThe positive standard potential supports a spontaneous galvanic reaction as written.
Problem: Find Mn in KMnO₄.
(+1) + Mn + 4(−2) = 0Mn = +7Problem: A metal coating is deposited on an object.
The object is the cathode because metal ions gain electrons there and become solid metal.
Problem: Magnesium is attached to an iron pipeline.
Magnesium oxidizes more readily and supplies electrons, so it corrodes in place of the iron.
Check before you commit
- Sending electrons through the salt bridge
- Saying reduction happens at the anode
- Changing the anodecathode reaction rule between cell types
- Calling the oxidized species the oxidizing agent
- Adding reduction potentials without reversing the anode term
- Assuming a positive ion plates at the anode
Do you need the lesson-or just practice?
One original question in each form recommends your next step. It does not yet verify mastery.
Work at the level you need.
Foundations
Build the core procedure with immediate explanations.
Core Practice
Use mixed forms with less scaffolding.
UPCAT-Style Transfer
Apply the competency in unfamiliar representations.
Ready to verify this competency?
A score of 5/5 verifies mastery. An unsuccessful attempt loads a different five-form bank.
Electrochemistry FAQ
Are anode and cathode signs always the same?
No. Their reaction roles stay fixed, but their signs differ between galvanic and electrolytic cells.
What moves through the salt bridge?
Ions, not electrons, move to maintain electrical neutrality.
Why does a positive E°cell matter?
Under standard conditions it indicates that the redox reaction is thermodynamically favored in the written direction.
Continue your mathematics review.
Your progress stays on this browser.
Mastery results save to your Teacher Abi study profile.
Return to Student Hub View UPCAT Coverage
No comments:
Post a Comment