In an Electrolytic cell, a current of 0.250 amps is passed through a solution of a chloride of iron, producing

Question

In an Electrolytic cell, a current of 0.250 amps is passed through a solution of a chloride of iron, producing Fe and Cl2.

When the cell operates for 2.00 hours, 0.521g of iron is deposited at one electrode. Determine the formula of the chloride of iron in the original solution.

I've been tryin to do this problem for almost 2 hours now. can someone help clarify things for me please! thanks

Answer 1

The net charge that passes through the soln = 0.25*2*3600
=1800 coulomb

No of moles of Fe deposited = 0.521/56=9.30*10^-3
let oxidation state of Iron = n
No of equivalents of Fe deposited = 9.30*10^-3*n
But 96500 Cs of charge liberates 1 eq of substance, so 1800 c charge liberates 1800/96500 eqs of substance.

1800/96500 =9.30*10^-3*n
or, n =1800/[96500*9.30*10^-3] = 2
ie, Fe is present as Fe2+ ion.

so, the salt is Ferrous chloride (FeCl2)

Answer 2

Total charge = 2*60*60*0.25 = 1800 C

Moles of Fe = 0.521/56

Let oxdn state of Fe = n

So, 1800/(n*96500) = 0.521/56

or n = 2

Thus the formula is FeCl2 (Ferrous Chloride).

Answer 3

Let coulomb be called C. 0.5hr x 60min/1hr x 60sec/1min x 10C/1sec x 1eqwtAu/96,500C x 1molAu/3eqwtAu x 197gAu/1molAu = 12g Au to 2 significant figures