a) To calculate the time required for the deposition of 0.387g of Tl3+ as Tl(s) on a cathode, we need to use Faraday's law of electrolysis, which states that the amount of substance deposited is directly proportional to the amount of charge passed through the electrolytic cell.
The equation for the reduction of Tl3+ to Tl is:
Tl3+ + 3e- -> Tl(s)
The number of moles of Tl3+ required for the deposition of 0.387g can be calculated as follows:
n(Tl3+) = m/M = 0.387g / (204.38 g/mol) = 0.001893 mol
The number of coulombs of charge required for the reduction of 0.001893 mol of Tl3+ can be calculated using Faraday's constant (F):
Q = n(F) = 0.001893 mol x (3 F/mol) = 0.005679 C
The time required for the deposition of 0.005679 C of charge at a constant current of 0.831A can be calculated using the formula:
t = Q/I = 0.005679 C / 0.831A = 6.83 seconds
Therefore, it would take approximately 6.83 seconds for a constant current of 0.831A to deposit 0.387g of Tl3+ as Tl(s) on a cathode.
b) To calculate the mass of Tl2O3(s) that can be deposited on an anode at a constant current of 0.831A over the same amount of time as calculated previously, we need to use the oxidation half-reaction for the formation of Tl2O3:
4 Tl(s) + 3 O2(g) -> 2 Tl2O3(s)
The number of moles of Tl2O3 that can be formed can be calculated as follows:
n(Tl2O3) = (n(Tl) / 4) = (Q / (4 F)) = (0.005679 C / (4 F)) = 0.000432 mol
The mass of Tl2O3 can then be calculated using its molar mass:
m(Tl2O3) = n(Tl2O3) x M(Tl2O3) = 0.000432 mol x (457.39 g/mol) = 0.197 g
Therefore, the mass of Tl2O3 that can be deposited on an anode at a constant current of 0.831A over the same amount of time as calculated previously is approximately 0.197 g.
*IG:whis.sama_ent*