Question

A current of 0.80 A was applied to a cell containing molten CdCl2 for 2.5 hours. Calculate the mass of cadmium metal deposited. Assume 100% current efficiency. Pick the best answer. OA) 1.2 x 10-3g OB) 8.4 g OC) 16.88 OD) 3.2 x 10-7g OE) 4.2 g

Answer 1

option E) 4.2 g of Cd deposited

Electrode equation is follows

Cu²⁺ + 2 e^- $\rightarrow$ Cu

The quantity of electricity passed in coulombs = current in A x time in sec

ie; Q = I x t

Q = 0.80 x 2.5 x 60 x 60

Q = 7200 C

one mole of electrons = 96500 C

Therefore, the moles of electrons passed through the circuit = 7200 / 96500

= 0.07461

It takes 2 moles of electrons to form one mole of Cd

Hence, mole of Cd = 0.07461 / 2

=0.03730

Mass of Cd = moles of Cd x atomic mass of Cd (112.411 u)

= 0.03730 x 112.411

= 4.2 g

ie; option E) 4.2 g of Cd deposited