Question

How long (in hours) must a current of 5.0 amperes be maintained to electroplate 60g of calcium from molten CaCl₂?

• A. 27 hours
• B. 8.3 hours
• C. 11 hours
• D. 16 hours

Hint:

Use Faraday’s law to calculate electrolysis time by relating the current, molar mass, and number of electrons involved.

Answer 1

The Correct Option is B

Step 1: Faraday’s law of electrolysis.
The amount of substance deposited in electrolysis is given by: \[ m = \frac{M I t}{n F} \] where \( M \) is the molar mass of calcium, \( I \) is the current, \( t \) is the time, \( n \) is the number of electrons involved, and \( F \) is Faraday's constant. Using the given values, we can calculate the time \( t \).

Step 2: Conclusion.
Thus, the time required is 8.3 hours. Hence, the correct answer is option (B).

Final Answer: \[ \boxed{\text{(B) 8.3 hours}} \]