What number of moles of Cu²⁺ will be deposited by 360 coulombs of electricity? [F = 96500 C mol⁻¹]

Correct answer: 1.87 × 10⁻³ mol (Option B)

Explanation: Deposition of copper at the cathode follows: Cu²⁺ + 2 e⁻ → Cu(s). Thus, 2 moles of electrons are needed per 1 mole of Cu deposited.

• Charge passed: \(Q = 360\ \text{C}\)
• Faraday constant: \(F = 96500\ \text{C mol}^{-1}\)
• Moles of electrons: \(n_e = \dfrac{Q}{F} = \dfrac{360}{96500} \approx 3.73 \times 10^{-3}\ \text{mol e}^-\)
• Moles of Cu deposited: \(n_{\text{Cu}} = \dfrac{n_e}{2} \approx \dfrac{3.73 \times 10^{-3}}{2} = \mathbf{1.87 \times 10^{-3}\ \text{mol}}\)

Why the others are incorrect: They correspond to using the wrong electron stoichiometry (e.g., dividing or not dividing by 2) or rounding errors. Only dividing the electron moles by 2 (because of Cu²⁺) gives the correct value.