A voltaic cell is also known as a galvanic cell. It is an electrochemical cell. It converts chemical energy into electrical energy through a spontaneous redox reaction.
Key Components:
- Two Half-Cells: Each half-cell consists of an electrode. The electrode is a metal strip. It is immersed in an electrolyte solution containing ions of that metal.
- Electrodes:
- Anode: The electrode where oxidation occurs (loss of electrons).
- Cathode: The electrode where reduction occurs (gain of electrons).
- Electrolyte: A solution containing ions that conduct electricity.
- Salt Bridge or Porous Membrane: Connects the two half-cells, allowing the flow of ions to maintain electrical neutrality.
How it Works:
- Spontaneous Redox Reaction: In a voltaic cell, a spontaneous redox reaction takes place. In one half-cell, the metal electrode loses electrons (oxidation) and releases metal ions into the solution. In the other half-cell, metal ions in the solution gain electrons (reduction) and deposit onto the electrode.
- Electron Flow: The electrons released at the anode travel through an external wire, creating an electric current. This flow of electrons from the anode to the cathode is the source of electrical energy.
- Ion Flow: To maintain electrical neutrality, ions flow through the salt bridge or porous membrane. Positive ions (cations) move towards the cathode, while negative ions (anions) move towards the anode.
Example:
A common example is the Daniell cell, which uses zinc and copper electrodes.
- Zinc Electrode (Anode): Zn(s) → Zn2+(aq) + 2e- (oxidation)
- Copper Electrode (Cathode): Cu2+(aq) + 2e- → Cu(s) (reduction)
Applications:
- Batteries: Common batteries like alkaline and zinc-carbon batteries are examples of voltaic cells.
- Fuel Cells: These devices use a continuous supply of fuel to generate electricity.
- Electroplating: Voltaic cells can be used to deposit a thin layer of one metal onto another.
Key Points:
- Voltaic cells convert chemical energy into electrical energy.
- They rely on spontaneous redox reactions.
- Essential components include two half-cells, electrodes, an electrolyte, and a salt bridge or porous membrane.
- They have various applications in everyday life and industry.