In a galvanic cell why anode is negative and cathode is positive

An electrochemical cell is an apparatus that either:

• Generates electricity from a spontaneous redox reaction, or
• Uses electricity to drive a non-spontaneous redox reaction.

A galvanic (voltaic) cell converts the energy released during a spontaneous redox reaction into electrical energy.

Example: Zinc and Copper Reaction

Consider the reaction between metallic zinc and cupric ions (Cu²⁺), which produces copper metal and zinc ions (Zn²⁺).

Balanced Chemical Equation:

Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)

• When a zinc rod is placed in an aqueous solution of copper(II) sulfate (CuSO₄):
  • The zinc rod dissolves as zinc atoms are oxidized to Zn²⁺ ions.
  • Simultaneously, copper ions in solution are reduced and deposited as metallic copper.
• Electrodes:
  • Anode (negative): Zinc electrode, where oxidation occurs (Zn → Zn²⁺ + 2e⁻).
  • Cathode (positive): Copper electrode, where reduction occurs (Cu²⁺ + 2e⁻ → Cu)