Question

When \(4\) A current was passed through a salt solution for \(45\) minutes, \(2.977\) g metal was deposited. Calculate the charge on metal ion having molar mass \(106.4\) g mol\({}^{-1}\).

• A. \(+1\)
• B. \(+2\)
• C. \(+3\)
• D. \(+4\)

Hint:

Find the total charge passed, then the moles deposited, and divide to get the number of electrons per ion.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept
The charge passed is \(Q=It\). Each metal ion of charge \(z\) needs \(z\) electrons, so \(Q=z\,F\,n\), where \(n\) is the moles deposited.

Step 2: Charge Passed
\(Q=4\times45\times60=10800\,\text{C}\)

Step 3: Moles Deposited
\(n=\dfrac{2.977}{106.4}=0.02798\,\text{mol}\)

Step 4: Calculation
\(z=\dfrac{Q}{F\,n}=\dfrac{10800}{96500\times0.02798}=\dfrac{10800}{2700}=4\)

Step 5: Conclusion
The charge on the ion is +4, option (D).

Final Answer:
The metal ion carries a charge of +4. \[ \boxed{\text{(D) }+4} \]