How long will it take to plate out each of the following with a current of 100.0 A?

a. 1.0 kg #Al# from aqueous #Al^(3+)#
b. 1.0 g #Ni# from aqueous #Ni^(2+)#
c. 5.0 mol #Ag# from aqueous #Ag^+#?

1 Answer
Al E.
Jan 3, 2018

The key here is translating the electrons required into faradays. Moreover,

#1A = (1C)/s#

This is basically a long unit conversion problem, I will do each in turn, below,

#1.0kg * (10^3g)/(kg) * ("mol")/(27.0g) * (3"mol"e^-)/("mol") * (96485"C")/("mol"e^-) * s/(100.0"C") approx 30"hr"#

I've omitted the time conversions above for brevity's sake, and will do so if the #"s"# answer is unreasonably high subsequently. Basically #1"hr" = 60min = 60"s"#.

#1.0g * ("mol")/(58.7g) * (1"mol"e^-)/("mol") * (96485"C")/("mol"e^-) * (s)/(100.0"C") approx 16"s"#

#5.0"mol" * (1"mol"e^-)/("mol") * (96485"C")/("mol"e^-) * (s)/(100.0"C") approx 1.3*10^4"hr"#

These are pretty common on exams, I would familiarize yourself with them and practice some more given the models I've supplied above.

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