Galvanic or Voltaic Cells

First identify the two redox couples. Next decide which species is oxidised and which is reduced using reactivity or electrode potential data. Then assign anode to oxidation and cathode to reduction. Finally write the cell notation with salt bridge symbol between the two half-cells.

A diagram should show two beakers, Zn electrode in Zn₂⁺ solution, Cu electrode in Cu₂⁺ solution, salt bridge between solutions, voltmeter in external circuit, electron flow from Zn to Cu, and ion migration through salt bridge.

A common wrong answer is assigning copper as anode in the Daniell cell because copper appears on the right side of the diagram, or saying salt bridge carries electrons.

A galvanic or voltaic cell is an electrochemical cell in which a spontaneous redox reaction converts chemical energy into electrical energy.

A galvanic or voltaic cell is an electrochemical cell in which a spontaneous redox reaction converts chemical energy into electrical energy. Cell notation rule: anode | anode ion || cathode ion | cathode. Oxidation half-reaction for Daniell cell: Zn(s) → Zn2+(aq) + 2e-. Reduction half-reaction: Cu2+(aq) + 2e- → Cu(s). Overall reaction: Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s). Daniell cell notation is Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu(s). Zinc is the anode, copper is the cathode, and electrons flow from Zn electrode to Cu electrode through the wire.

In a galvanic cell, oxidation occurs at the anode and reduction occurs at the cathode. In the Daniell cell, zinc metal loses electrons to form zinc ions, while copper ions gain electrons to form copper metal. Electrons move through the external circuit from zinc to copper, while ions move through the salt bridge to maintain electrical neutrality in both half-cells. The salt bridge does not supply electrons; it completes the internal ionic circuit and prevents charge build-up. Cell notation rule: anode | anode ion || cathode ion | cathode. Oxidation half-reaction for Daniell cell: Zn(s) → Zn2+(aq) + 2e-. Reduction half-reaction: Cu2+(aq) + 2e- → Cu(s). Overall reaction: Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s). For the cell Zn | Zn₂⁺ || Cu₂⁺ | Cu, identify the electrode reactions. Since zinc is on the left, it acts as anode: Zn(s) → Zn₂⁺ + 2e-. Copper ion is reduced at the cathode: Cu₂⁺ + 2e- → Cu(s). Adding gives Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s). Questions usually ask students to label anode, cathode, electron flow, salt bridge function, cell reaction, or cell notation for a given redox pair. A common wrong answer is assigning copper as anode in the Daniell cell because copper appears on the right side of the diagram, or saying salt bridge carries electrons.