Question

How many Faraday electricity is required to reduce 0.25 g of Nb(V) to the metal? ( Atomic mass of Nb = 93)

• A. \(2.7\times 10^{-3}\)
• B. \(1.3\times 10^{-2}\)
• C. \(3.7\times 10^{-2}\)
• D. \(7.8\times 10^{-3}\)

Hint:

Five electrons are needed per Nb atom, so multiply the moles of Nb by 5.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
The reduction is \(\text{Nb}^{5+}+5e^-\rightarrow\text{Nb}\). So 5 faradays are needed per mole of Nb.

Step 2: Moles of Nb
\(n=\dfrac{0.25}{93}=2.69\times 10^{-3}\) mol.

Step 3: Calculation
Faradays \(=n\times 5=2.69\times 10^{-3}\times 5=1.34\times 10^{-2}\approx 1.3\times 10^{-2}\) F.

Final Answer:
About 1.3 times 10 to the power minus 2 faraday is required, which is option (B). \[ \boxed{\text{(B) }1.3\times 10^{-2}} \]