Question

The current efficiency of an electro deposition of copper metal in which 9 g of copper is deposited by passing a current of 3 ampere for 2 hours 40 minutes and 50 seconds is:

• A. 90.1%
• B. 92.1%
• C. 93.1%
• D. 95.5%

Answer 1

The correct option is D 95.5%

Amount of Cu deposited = 9 g.

For one mole of $C{u}^{2+}$ deposited, two electrons are involved as,

$C{u}^{2+}+2e^{-}$ $\to$ Cu

Total amount of Coulombs for the deposition of one mole = 2 x 96500
=1,93,000

Amount of Coulombs utilised during the reaction,
Time, t = 9650 s

= It
= $3\times 9650$

Therefore, amount of Cu deposited=$\frac{28950}{1,93,000}$
=0.15 mole

Weight of Cu= 0.15 x 63.5
= 9.525 g

Efficiency= $\frac{9}{9.5}\approx 95.5$