Question

A current of 5.42 A is passed through a Ni(NO3)2 solution. How long (in hours) would this current have to be applied to plate out 5.00 g of nickel? (Please show all steps)

Answer 1

Convert the mass of Ni produced into moles using the molar mass of Ni = 5 /58.7 = 0.0851 Mole

half-reaction for the production of Ni at the cathode = Ni²⁺(aq) + 2 e^- Ni(s)

the moles of e^- required to produce the moles of Ni using the stoichiometry of the balanced half-reaction.   According to the equation 2 moles of electrons will produce one mole of Nickel

                                     = 0.0851 Mole x 2 mole of e- / 1mole of Nickel = 0.1703 mole e-

Convert the moles of electrons into coulombs of charge using Faraday's constant.

                                      = 0.1703 x 1F / 1 mole of e- =0.1703 F

                                      = 0.1703 x 96485 C/ 1F = 16436

Calculate the time using the current and the coulombs of charge.

                               5.42 Amps x t = 16436 C

                                                  t = 16436 / 5.42 = 3032 Sec or 50.53 Min or 0.84 hours