Calculate the quantity of electricity in coulombs required to liberate 10g of copper from a copper compound [Cu=64, F = 96500 C$mol^{-1}$]

Analysis

To solve this problem, we need to use Faraday’s Laws of Electrolysis. We are given the mass of the substance to be liberated, its molar mass, and the Faraday constant. We need to find the total charge ($Q$) in Coulombs.

Concept

The reaction for the deposition of copper from a copper(II) compound is:

From this equation, we see that 2 moles of electrons are required to deposit 1 mole of copper.

• 1 mole of electrons = 1 Faraday ($F$) = 96,500 Coulombs.
• Therefore, 2 moles of electrons = $2 \times 96,500$ Coulombs.

Step-by-Step Solution

Step 1: Determine the number of moles of copper.

Step 2: Determine the quantity of electricity required. Since 1 mole of Cu requires $2 \times 96,500$ C:

Rounding to one decimal place as seen in the options, we get 30,156.3 C.

Conclusion

Comparing our result to the provided options, the calculated value matches option B.

Exam Tip

Always check the valency of the metal in the compound. If the question had said "Copper(I) chloride," the valency would be 1, and you would not multiply by 2. Since it says "copper compound" without specifying, and copper is typically $Cu^{2+}$ in common electrolysis problems, using a valency of 2 is the standard approach.