How many grams of cobalt may be formed by the passage of 3.57 amps for 1.44 hours through an electrolytic cell that contains an aqueous cobaltic (Co(III)) salt.

Answer 1

Co³⁺ + 3e- ==> Co(s)

Convert amps to coulombs per second:

3.57 amps = 3.57 C/s

Find total coulombs applied:

1.44 hours x 60 min/hour x 60 sec/min x 3.57 C/s = 18,507 C

Use number of coulombs to find moles of Co that can be reduced (recall 1 mol e- requires 96,485 C):

18,507 C x 1 mol e-/96,485 C x 1 mol Co/3 mol e- = 0.06394 moles Co

Finally, convert moles Co to grams Co:

0.06394 mol Co x 58.93 g/mol = 3.77 g