The quantity of electricity required to discharge 1 mole of univalent ion is

Analyze the question: It asks for the charge needed to discharge 1 mole of a univalent ion (an ion with a charge of 1, such as Na⁺ or Cl⁻).

Concept: One Faraday (1 F) is the quantity of electricity carried by 1 mole of electrons.

• Charge on one electron = 1.602 × 10⁻¹⁹ C
• Avogadro's number = 6.02 × 10²³ electrons per mole

Solution:

1 F = (1.602 × 10⁻¹⁹ C) × (6.02 × 10²³ mol⁻¹) ≈ 96,500 C/mol

A univalent ion needs 1 mole of electrons to be discharged, for example:

Na⁺ + e⁻ → Na

So 1 mole of Na⁺ needs 1 mole of electrons, which is 1 Faraday, or 96,500 C.

Checking the options:

• A. 9,600 C is too small by a factor of 10.
• B. 48,250 C is half a Faraday.
• C. 96,500 C is 1 Faraday, which is correct.
• D. 193,00 C is a misprint of 193,000 C, which is 2 Faradays. That would discharge a divalent ion such as Cu²⁺.

Tip: Remember that charge needed = n × F, where n is the charge on the ion. For a univalent ion, n = 1, so the charge is 96,500 C. For a divalent ion it is 2 × 96,500 = 193,000 C, and for a trivalent ion such as Al³⁺ it is 3 × 96,500 = 289,500 C.