Question

Match the following and select the correct option for the quantity of electricity, in Cmol\(^{-1}\), required to deposit various metals at the cathode.

• A. \( \text{Ag}^+ \), ii) 386000 Cmol\(^{-1}\)
• B. \( \text{Mg}^{2+} \), iii) 289500 Cmol\(^{-1}\)
• C. \( \text{Al}^{3+} \), iv) 96500 Cmol\(^{-1}\)
• D. \( \text{Ti}^{4+} \), i) 193000 Cmol\(^{-1}\)

Hint:

Remember, the quantity of electricity required is inversely proportional to the number of electrons involved in the redox reaction.

Answer 1

The Correct Option is A

The quantity of electricity (Cmol\(^{-1}\)) required to deposit a metal is inversely proportional to the number of electrons required to deposit one mole of metal. The relationship follows from the equation: \[ Q = \frac{nF}{z} \] Where: - \( Q \) is the charge in coulombs, - \( n \) is the number of moles of electrons, - \( F \) is the Faraday constant (96500 Cmol\(^{-1}\)), - \( z \) is the valency of the metal ion. For the metals listed, the corresponding values of \( Q \) can be matched as follows: - \( \text{Ag}^+ \) (1 electron) needs 386000 Cmol\(^{-1}\), - \( \text{Mg}^{2+} \) (2 electrons) needs 289500 Cmol\(^{-1}\), - \( \text{Al}^{3+} \) (3 electrons) needs 96500 Cmol\(^{-1}\), - \( \text{Ti}^{4+} \) (4 electrons) needs 193000 Cmol\(^{-1}\). Thus, the correct matching is a-iii, b-iv, c-ii, d-i.