Galvanic cells convert chemical energy into electrical energy through redox reactions. These cells consist of two half-cells connected by a salt bridge, with electrons flowing from the anode to the cathode through an external circuit.

Understanding galvanic cell components is crucial for grasping electrochemistry concepts. The anode undergoes oxidation, releasing electrons, while the cathode accepts electrons in a reduction reaction. The salt bridge maintains charge balance, allowing for continuous electron flow.

Galvanic Cell Components and Function

Components of galvanic cells

• Anode oxidation occurs releases electrons negative electrode
  • $Zn(s) \rightarrow Zn^{2+}(aq) + 2e^-$ (in Zn-Cu cell)
• Cathode reduction occurs accepts electrons positive electrode
  • $Cu^{2+}(aq) + 2e^- \rightarrow Cu(s)$ (in Zn-Cu cell)
• Salt bridge allows ion flow maintains charge balance prevents mixing of half-cell solutions
  • Contains $KCl$ or $KNO_3$ solution (in Zn-Cu cell)
• Voltmeter measures potential difference (voltage) between electrodes
  • Typical values range from 0.1 V to 3 V (Zn-Cu cell ~1.1 V)
• Half-cells each electrode immersed in electrolyte solution containing its ions
  • Oxidation half-cell contains anode species being oxidized ($Zn$ in $Zn^{2+}$ solution)
  • Reduction half-cell contains cathode species being reduced ($Cu$ in $Cu^{2+}$ solution)
• Electron flow occurs from anode to cathode through external circuit

Cell notation for galvanic cells

• Shorthand representation of galvanic cells
• General format: Anode | Anode Electrolyte || Cathode Electrolyte | Cathode
  • Anode on left cathode on right
  • Single vertical line (|) separates electrode from electrolyte
  • Double vertical line (||) separates two half-cells
• $Zn(s) | Zn^{2+}(aq) || Cu^{2+}(aq) | Cu(s)$
  • $Zn$ is anode $Cu$ is cathode
  • $Zn^{2+}$ and $Cu^{2+}$ are electrolytes in respective half-cells

Active vs inert electrodes

• Active electrodes participate in redox reaction
  • Electrode material consumed or deposited during reaction
  • $Zn$, $Cu$, $Ag$, $Mg$
• Inert electrodes do not participate in redox reaction
  • Electrode material acts as surface for electron transfer
  • $Pt$, $Au$, $graphite$
• In $Zn$-$Cu$ galvanic cell:
  • $Zn$ is active electrode (anode) oxidized and consumed
  • $Cu$ is active electrode (cathode) $Cu^{2+}$ reduced and deposited on electrode

Electrochemical Potentials and Calculations

• Standard electrode potential (E°) measures tendency of half-reaction to occur
• Electrochemical series ranks half-reactions by standard reduction potentials
• Nernst equation relates cell potential to concentration and temperature
• Electrochemistry studies chemical reactions involving electric charges