Question

Tse the References to access important valnes if meeded for this westion. A galvanic cell Fe(s) Fe (aNaNi(s) is constructed using a completely immersed Fe electrode that weighs 37.1 g and a Ni electrode ismersed in 473 mL of 1.00 MN(aq) solution A steady current of 0.0769 A is drawn fom the cell as the electrons move fro the Fe electrode to the Ni electrode. a) Which reactant is the limiting reactant in this eell? Enter symbel (b) How long does it take for the cell to be completely discharged? (c) How much mass has the Ni electrode gained when the cell is completely discharged? (d) what is the concentration ofthe Ni2-(aq) when the cell is completely discharged? (Assume that the limitin reactamt is 100% reacted)

Answer 1

Given data,

mass = 37.1 g

Volume = 473 mL

Current = 0.0769 A

Given galvanic cell is

Fe(s)|Fe^2+(aq) || Ni^2+(aq) Ni(s)

a)

Mole of Fe = Mass / Molar mass

= 37.1 g / 55.84 g/mol

= 0.664 mol

Moles of Ni^2+ = Molarity x Volume

= 1 M x 473 x 10^-3

= 0.473 mol

Here Fe is limiting reagent

b)

From Faraday's electrolysis,

W = Mct / ZF

t = wzF / MC

= 37.1 x 2 x 96500 / 55.84 x 0.0769

= 7160300 / 4.294

= 1667512 sec

c)

1 mol of Fe dissolved = 1 mol of Ni dissolved

0.664 mol of Fe dissolved = 0.664 mol of Ni deposited

Mass of Ni = 0.664 x 58.69

= 38.97 g

d)

Remaining moles of Ni^2+ in the solution after completion of reaction = 0.664 - 0.473

= 0.191 mol

[Ni^2+] = 0.191 x 1000 / 473

= 191 / 473

= 0.403 M