Determine how long it takes to cover both sides of the plate

[DevonZA]

A square plate has a side of 100mm. It is connected to the cathode in a copper electroplating bath and a current of 4A is passed through the bath. Neglecting the thickness of the plate, determine how long it takes to cover both sides of the plate with copper to thickness of 0.1mm

Density of copper to be 9000kg/m^3
The electrochemical equivalent of copper to be 0.330mg/C

Answer given = 227 min 16 sec

Volume = area x height
= 20 000x10^-7 X 0.23x10^-3
= 4x10^-7

Mass = volume x density
= 4x10^-7 X 9000kg/m^3
= 3.6x10^-3kg = 3600mg

m = zIt
t = m/zI
= 3600/(0.330)(4)
= 43636.36364s = 727 min and 16 sec

I am quite confident in my answer but it is way off from the supplied answer - unless that was a typo.
Any input would be appreciated.

Thanks,
Devon

 

[ehild]

A square plate has a side of 100mm. It is connected to the cathode in a copper electroplating bath and a current of 4A is passed through the bath. Neglecting the thickness of the plate, determine how long it takes to cover both sides of the plate with copper to thickness of 0.1mm

Density of copper to be 9000kg/m^3
The electrochemical equivalent of copper to be 0.330mg/C

Answer given = 227 min 16 sec

Volume = area x height
= 20 000x10^-7 X 0.23x10^-3
= 4x10^-7

Where are the red numbers from?

 

[mfb]

Volume = area x height
= 20 000x10^-7 X 0.23x10^-3

Where do those numbers come from and what are their units?

Edit: ehild beat me.

 

[DevonZA]

Where are the red numbers from?

square plate has 100mm side, therefore area = 100mmx100mm=10000mm^2 X 2 sides = 20000mm^2 = 20000x10^-7
copper thickness = 0.1mm each side = 0.2mm = 0.2x10^-3

Sorry should have been 0.2x10^-3 not 0.23x10^-3

 

[mfb]

1mm^2 = 10^-7? An area is a number?
If that is supposed to be square meters, the number is wrong.

I can confirm the given answer.

 

[ehild]

square plate has 100mm side, therefore area = 100mmx100mm=10000mm^2 X 2 sides = 20000mm^2 = 20000x10^-7
copper thickness = 0.1mm each side = 0.2mm = 0.2x10^-3

Sorry should have been 0.2x10^-3 not 0.23x10^-3

You counted the two sides twice. And 1 mm²=10^-6 m².

 

[DevonZA]

1mm^2 = 10^-7? An area is a number?
If that is supposed to be square meters, the number is wrong.

I can confirm the given answer.

What is 20000mm^2 in m^2?

 

[DevonZA]

You counted the two sides twice. And 1 mm²=10^-6 m².

How did I count them twice? 1 side = 100mmx100mm = 10 000mm² so 2 sides = 20 000mm²

 

[mfb]

What is 20000mm^2 in m^2?

1mm = 10^-3m, square both sides, or see post 6.

To get closer to the given answer, you might also want to use a more precise density estimate for copper, but that just changes the result by about one minute.

 

[ehild]

How did I count them twice? 1 side = 100mmx100mm = 10 000mm² so 2 sides = 20 000mm²

After that, you said that 0.1 mm layer on both sides, so it is 0.2 mm on both sides.

 

[DevonZA]

1mm = 10^-3m, square both sides, or see post 6.

To get closer to the given answer, you might also want to use a more precise density estimate for copper, but that just changes the result by about one minute.

Alright so 20 000mm² = 20 000 x10^-6?
If I use that number I get an answer of 7272 min
The density was given as 9000kg/m³

 

[DevonZA]

After that, you said that 0.1 mm layer on both sides, so it is 0.2 mm on both sides.

I see what you mean, thank you.

volume = 20 000x10^-7 X 0.1x10^-3
= 2x10^-7

mass = 2x10^-7 X 9000kg/m³
= 1.8x10³kg = 1800mg

t = m/zI
= 1800/(0.33)(4)
= 1363.636364s = 22 min 43 seconds

 

[mfb]

Now you used the wrong 10^-7 again. Apart from that it is right.

 

[DevonZA]

volume = 20 000x10^-6 X 0.1x10^-3
= 2x10^-6

mass = 2x10^-6 X 9000kg/m3
= 0.018kg = 18000mg

t = m/zI
= 18000/(0.33)(4)
= 13636.36364s = 227 min 16 seconds

My goodness finally. Thank you very much mfb and ehild for your help!