Describe the Daniell cell with a labelled diagram. Write the electrode reactions, the cell notation and the functions of the salt bridge.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Define. A galvanic cell converts the chemical energy of a spontaneous redox reaction into electrical energy. The Daniell cell is one example.
2 · Draw the cell. Zn rod in ZnSO₄ (left), Cu rod in CuSO₄ (right), salt bridge joining the solutions, voltmeter in the wire. Label anode (−), cathode (+) and the direction of electron flow.
3 · Write the half-reactions.
Anode (oxidation): Zn(s) → Zn²⁺(aq) + 2e⁻
Cathode (reduction): Cu²⁺(aq) + 2e⁻ → Cu(s)
Overall: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)
4 · Write the notation and EMF.Zn(s) | Zn²⁺(aq, 1 M) || Cu²⁺(aq, 1 M) | Cu(s); E°cell = 0.34 − (−0.76) = 1.10 V.
5 · Give the salt bridge's functions.
Completes the inner circuit by letting ions move
Keeps both solutions electrically neutral
6 · Link to real life. Torch and clock cells are galvanic cells; a lemon battery works the same way.
7 · Close in one line. So the zinc rod slowly wears away while copper builds up on the copper rod.
Scoring tip: Draw the electron-flow arrow in the wire from zinc to copper. Many students draw it backwards.
