In Volta's demonstration, what was placed between the silver and zinc electrodes?

In Volta's demonstration, what was placed between the silver and zinc electrodes?

• A. A sheet of mica
• B. Paper towel soaked in plain water
• C. A wad of cotton soaked in saline
• D. Cardboard soaked in saltwater

Answer: (D)

The main idea is that a medium allowing ions to move between the electrodes is needed to complete the circuit in a galvanic setup. In Volta’s pile, a piece of cardboard soaked in saltwater served as both separator and electrolyte between each pair of metal discs. The salty solution provides ions that carry charge internally, letting the redox reactions at the zinc and silver surfaces push electrons through the external circuit without the plates shorting together. A sheet of mica would block ion flow since it’s an insulator. Plain water without salt has far fewer ions to carry charge, so conduction would be poor and the current would drop quickly. Cotton soaked in saline could work, but cardboard soaked in saltwater was used because it’s a good, porous separator that stays moist and evenly separates the plates.

The main idea is that a medium allowing ions to move between the electrodes is needed to complete the circuit in a galvanic setup. In Volta’s pile, a piece of cardboard soaked in saltwater served as both separator and electrolyte between each pair of metal discs. The salty solution provides ions that carry charge internally, letting the redox reactions at the zinc and silver surfaces push electrons through the external circuit without the plates shorting together. A sheet of mica would block ion flow since it’s an insulator. Plain water without salt has far fewer ions to carry charge, so conduction would be poor and the current would drop quickly. Cotton soaked in saline could work, but cardboard soaked in saltwater was used because it’s a good, porous separator that stays moist and evenly separates the plates.