Voltaic Cells Quiz

Voltaic Cells

• Voltaic cells use a chemical reaction to produce electricity.
• Voltaic cells utilize oxidation-reduction reactions.
• A battery is a common example of a voltaic cell.

Basic Voltaic Cell Setup

• Two beakers, each containing a solution: one with zinc sulfate and the other with copper sulfate.
• A piece of zinc metal is placed in the zinc sulfate solution.
• A piece of copper metal is placed in the copper sulfate solution.
• A wire connects the zinc and copper metal, causing electrons to flow from zinc to copper.
• A salt bridge connects the two solutions.

Electron Movement

• Copper ions (Cu2+) have a stronger pull for electrons than zinc atoms.
• Zinc atoms lose electrons, becoming zinc ions (Zn2+) that dissolve in the solution.
• The lost electrons travel through the wire to the copper.
• Copper ions in the solution gain electrons, becoming neutral copper atoms that attach to the copper metal.
• This electron movement creates an electric current.

Oxidation and Reduction

• Oxidation: Loss of electrons, occurs at the anode (zinc metal).
• Reduction: Gain of electrons, occurs at the cathode (copper metal).
• Half Reactions:
  • Oxidation: Zn(s) → Zn2+(aq) + 2e-
  • Reduction: Cu2+(aq) + 2e- → Cu(s)
• Net Ionic Equation: Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)

Cell Notation

• A shorthand representation of the voltaic cell:
  • Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu(s)

Salt Bridge

• A tube filled with an electrolyte (e.g., sodium chloride) connecting the two solutions.
• Prevents a buildup of charge in each half-cell by allowing ions to flow between the solutions.
• Positive ions from the salt bridge move toward the negative side to balance charge.
• Negative ions from the salt bridge move toward the positive side to balance charge.

Overall Changes in the Voltaic Cell

• The zinc metal dissolves as atoms lose electrons and become ions in the solution.
• The copper metal increases in size as copper ions gain electrons and become neutral atoms that attach to the metal.
• The flow of electrons through the wire constitutes the electric current generated by the voltaic cell.