± Analysis of Electroplating The total charge of a mole of electrons is 96,485 c

Question

± Analysis of Electroplating

The total charge of a mole of electrons is 96,485 coulombs (C) and

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

Part A

What mass of Cu(s) is electroplated by running 21.0 A of current through a Cu2+(aq) solution for 4.00 h?

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

8.97g

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Part B

How many minutes will it take to electroplate 33.1 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.

19.8min

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± 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

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

Part A

What mass of Cu(s) is electroplated by running 21.0 A of current through a Cu2+(aq) solution for 4.00 h?

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

8.97g

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Incorrect; Try Again; 4 attempts remaining

Part B

How many minutes will it take to electroplate 33.1 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.

19.8min

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Explanation / Answer

1)

we know that

according to faradays first law of electrolysis

mass of metal deposited is

m = I x t x M / F x z

given

current (I) = 21

time (t) = 4 h = 4 x 60 min = 4 x 60 x 60 s = 14400 s

molar mass of copper (M) = 63.546 g /mol

F = faradays constant = 96485

z = charge = 2

so

using those values

we get

m = 21 x 14400 x 63.546 / 96485 x 2

m = 99.58

so

the mass of Cu(s) electroplated is 99.58 g

2)

m = I x t x M / F x z

here

mass electroplated (m) = 33.1 g

current (I) = 5

molar mass of gold (M) = 196.96657

z= charge = 1

so

33.1 = 5 x t x 196.96657 / 96485 x 1

t = 3242.8 s

t = 3242.8 / 60 min

t = 54

so

it takes 54 minutes

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