Electric current is measured in amperes (A), which expresses the amount of charg

Question

Electric current is measured in amperes (A), which expresses the amount of charge, in coulombs (C), that flows per second (s): 1 A = 1 C/s Another unit of charge is the faraday (F), which is equal to a mole of electrons and is related to charge in coulombs as follows: 1 F = 1 mol e- = 96,500 C Galvanized nails are iron nails that have been plated with zinc to prevent rusting. The relevant reaction is Zn2+ (aq) + 2e- rightarrow Zn(s) For a large batch of nails, a manufacturer needs to plate a total zinc mass of 2.70kg on the surface to get adequate coverage. How many coulombs charge are needed to produce 41.3 mol solid zinc? Express your answer to three significant figures and include the appropriate units. What mass of gold is produced when 16.6A of current are passed through a gold solution for 48 0 min ? Express your answer with the appropriate units.

Explanation / Answer

part 1

Zn(2+) + 2e(-) -------> Zn

1 mole of Zn is deposited by 2F of electricity ...
so 41.3 mole of Zn will be deposited by 41.3 X 2F = 82.6 F of electricity...

as 1F = 96500 C
so 82.6 F = 82.6 X 96500 = 7970900 C of electricity...

part 2

16.6 A for 48.0 min is

16.6 Coulomb/s x 48.0 min x 60 sec/min = 47808 Coulombs

One Faraday is 96,500 Coulombs

47808 Coulombs / 96,500 Coulombs / Faraday = 0.495 Faraday

Au3+ + 3e- >> Au

For every 3 Faradays of electricity used up , one mole Au forms.

0.495 Faraday x 1 mole Au/ 3 Faradays = 0.165 mole Au

One mole Au is 196.967 g

196.967 g/mol x 0.165= 32.53 g Au

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