Question

How long (in hours) must a current of $5.0$ A be maintained to electroplate $60$ g of calcium from molten $CaC{l}_2$?

• A. $27$ h
• B. $8.3$ h
• C. $11$ h
• D. $16$ h

Answer 1

Answer: (D)

$16$ h

Given: $w=60g,i=5A$

Equivalent of Ca$=\frac{Atomicweight}{Valency}=\frac{40}{2}=20$

According to first law of faraday electrolysis:

$w=Zit=\frac{Equivalentweight}{96500}\times i\times T$

$60=\frac{20}{96500}\times 5\times T$

$T=\frac{96500\times 60}{20\times 5}s$

$T=\frac{96500\times 60}{20\times 5\times 60\times 60}h$

$=16.08h.\approx 16h$

Hence, option D is correct.