When electricity (the flow of electrons) is passed through a solution, it causes

Question

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

1ampere(A)=1coulomb/second(C/s)

1. What mass of Cu(s) is electroplated by running 27.5 A of current through a Cu2+(aq) solution for 4.00 h?

Express your answer to three significant figures and include the appropriate units.

2. How many minutes will it take to electroplate 45.1 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

1. W = ZiT

w = (E/F)it

E = equivalent weight of Cu = 63.5/2 = 31.75

w =weight of Cu deposited = (31.75/96500*27.5*4*60*60)

   = 130.29 grams

2. equivalent weight of Au = 196.97/1 = 196.97

w = zit = E/Fit

45.1 = (196.97/96500)*5*t

t = 4419.1 sec

= 73.65 min

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