📖 Theory & Concepts ▼

Electrochemical Cell

A device that converts chemical energy to electrical energy through spontaneous redox reactions.

Anode (−): Zn → Zn²⁺ + 2e⁻ (Oxidation)
Cathode (+): Cu²⁺ + 2e⁻ → Cu (Reduction)
E°cell = E°cathode − E°anode

Daniell Cell (Zn-Cu)

  • E°(Zn²⁺/Zn): −0.76 V (more reactive, anode)
  • E°(Cu²⁺/Cu): +0.34 V (less reactive, cathode)
  • E°cell: 0.34 − (−0.76) = 1.10 V
Salt Bridge:

Maintains electrical neutrality by allowing ion flow. Usually KCl or KNO₃ in agar gel.

Voltmeter
00.51.01.52.0
0.00 V
ANODE (Oxidation)
Zn
ZnSO₄ (1M)
Zn → Zn²⁺ + 2e⁻
E° = -0.76 V
e⁻ →
Salt Bridge (KCl)
CATHODE (Reduction)
Cu
CuSO₄ (1M)
Cu²⁺ + 2e⁻ → Cu
E° = +0.34 V

Predict

Observe

Connect the circuit to observe electron flow, electrode mass changes, salt bridge ion movement, and EMF.

Explain

In a Daniell cell, zinc is the anode and copper is the cathode. A correct model shows metal dissolving at zinc and metal plating at copper, not gas bubbles.

Specific Safety

Copper sulphate and zinc sulphate solutions should be handled with goggles and gloves. Avoid skin contact, keep the salt bridge solution away from eyes, do not short the cell for long periods, and collect metal-salt waste separately instead of pouring it into a sink.

📚 Cell Notation

Zn | Zn²⁺(1M) || Cu²⁺(1M) | Cu
E°cell = E°cathode - E°anode
E°cell = 0.34 - (-0.76) = +1.10 V

Observations

Connect the circuit to begin...