Analysis of Electroplating When electricity (the flow of electrons) is passed th

Question

Analysis of Electroplating When electricity (the flow of electrons) is passed through a solution, it causes an oxidation - reduction (redox) reaction to occur. If the solution contains a metal cation such as Ag^+ , the flow of electrons will reduce the silver ion, causing solid silver to plate onto the electrode. The amount of metal plated depends on the number of electrons passed. The total charge of a mole of electrons is 96,485 coulombs (C) and 1 ampere (A) = 1 coulomb/second (C/s) Part A What mass of Cu(s) is electroplated by running 12.5 A of current through a Cu^2+ (aq) solution for 4.00 h? Express your answer to three significant figures and include the appropriate units. Part B How many minutes will it take to electroplate 12.1 g of gold by running 5.00 A of current through a solution of Au^+ (aq)? Express your answer to three significant figures and include the appropriate units.

Explanation / Answer

Part A)

current (i) = 12.5 A

time (t) = 4 h = 4 x 3600 = 14400 sec

equivalent weight of (Cu) E = atomic weight / charge = 63.55 /2 = 31.77

faradary = 96500C

from faraday's law :

w = E x ix t / 96500

     = 31.77 x 12.5 x 14400 / 96500

    = 59.3g

mass of Cu =59.3g

part B)

current (i) = 5 A

time (t) = ??

equivalent weight of (Au) E = atomic weight / charge = 196.97 /1 = 196.97

faradary = 96500C

mass deposited = 12.1 g

from faraday's law :

w = E x ix t / 96500

12.1 = 196.97 x 5 x t /96500

t = 1185.6sec

t = 19.8 min

time = 19.8 min

    = 59.3g

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