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Chemistry · Grades 10–12

Electrochemistry: electrodes and potentials

Keep oxidation and reduction identities separate from cell-specific signs.

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Learn the idea

Electrodes

Oxidation occurs at the anode and reduction at the cathode in both galvanic and electrolytic cells.

Cell types

Electrode signs differ between galvanic and electrolytic operation; do not memorize one sign without context.

Potential

Using reduction potentials, E°cell = E°cathode − E°anode.

Charge flow

Electrons travel in the external conductor; ionic motion carries charge through electrolyte.

Worked examples

At which electrode does oxidation occur?

Anode is defined by oxidation.

Anode.

At which electrode does reduction occur?

Cathode is defined by reduction.

Cathode.

Check your understanding

  1. Given reduction potentials +0.80 V at the cathode and −0.20 V at the anode, find E°cell.

  2. Should an electrode's positive or negative sign be inferred without knowing the cell type?

    1. No.
    2. Yes; cathodes are always negative.
    3. Yes; anodes are always positive.

  3. A current of 2 A flows for 30 s. What charge passes?

Answers and marking notes

Answers and marking notes
  1. 1 V

    0.80 − (−0.20) = 1.00 V.

  2. No.

    Galvanic and electrolytic cells have different sign relationships.

  3. 60 C

    Q = It = 2 × 30 = 60 C.

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.