Question

What is electrochemical cell? Explain the structure of an electrochemical cell.

Hint:

Remember: oxidation occurs at the anode, reduction at the cathode — “An Ox, Red Cat.”

Answer 1

Step 1: Definition.
An electrochemical cell is a device that converts chemical energy into electrical energy through redox reactions occurring in separate half-cells.
Step 2: Construction.
An electrochemical cell consists of:
- Two half-cells: one acts as the anode (oxidation) and the other as the cathode (reduction).
- A salt bridge that maintains electrical neutrality by allowing the flow of ions.
- Electrodes dipped into electrolyte solutions of their respective ions.
Step 3: Example — Daniell Cell.
\[ \text{Zn | Zn}^{2+} (aq) || \text{Cu}^{2+} (aq) | \text{Cu} \] Here, - At the anode: \( \text{Zn} \rightarrow \text{Zn}^{2+} + 2e^- \) (oxidation)
- At the cathode: \( \text{Cu}^{2+} + 2e^- \rightarrow \text{Cu} \) (reduction)
- Electrons flow from Zn to Cu through the external circuit.
Step 4: Working.
The redox reaction generates an electromotive force (emf) that drives the flow of electrons through the circuit.
Step 5: Cell notation and emf.
The overall reaction is: \[ \text{Zn} + \text{Cu}^{2+} \rightarrow \text{Zn}^{2+} + \text{Cu} \] Cell emf is given by: \[ E_{cell} = E_{cathode} - E_{anode} \] Step 6: Significance.
Electrochemical cells are used in batteries, corrosion studies, and electroplating.