# The Naked Scientists Forum

### Author Topic: Diference between "cupering" proces  (Read 4090 times)

#### Garabato

• Jr. Member
• Posts: 17
##### Diference between "cupering" proces
« on: 12/08/2007 22:40:12 »
Hi, do you guys know whats the theoretical diferemce between those proces? (they have the same apparent result.  A cuper cape is formed on an iron nail)

a. -Grab the (washed) iron nail
-Fill a beaker with CuSO4 1M
-Put the iron nail on it
-After 15 minutes, a small cape of cuper is formed around the iron nail.

b -In a clen beaker, put 50 ml of CuSO4 1M and 50 ml of H2SO4
-Use the iron nail as cathode and a cuper piece as anode. Introduce them in the beaker and conect it to a 6v battery.
-After 15 minutes, another small cape of cuper is formed around the iron nail.
« Last Edit: 16/08/2007 15:51:01 by daveshorts »

#### lightarrow

• Neilep Level Member
• Posts: 4586
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##### Re: Diference between "cupering" proces
« Reply #1 on: 13/08/2007 11:14:22 »
Hi, do you guys know whats the theoretical diferemce between those proces? (they have the same apparent result.  A cuper cape is formed on an iron nail)

a. -Grab the (washed) iron nail
-Fill a beaker with CuSO4 1M
-Put the iron nail on it
-After 15 minutes, a small cape of cuper is formed around the iron nail.

b -In a clen beaker, put 50 ml of CuSO4 1M and 50 ml of H2SO4
-Use the iron nail as cathode and a cuper piece as anode. Introduce them in the beaker and conect it to a 6v battery.
-After 15 minutes, another small cape of cuper is formed around the iron nail.
3Cu++ + 2Fe --> 2Fe+++ + Cu. This happens because the standard reduction potential of Cu is greater than that of Fe.

#### Cut Chemist

• Full Member
• Posts: 96
##### Re: Diference between "cupering" proces
« Reply #2 on: 16/08/2007 15:15:21 »
Process A is probably extremely slower, if it even occurs at all.
I think that electricity is required for plating metals, or perhaps it greatly speeds up the process.

The sulfuric acid is just to help all of the copper sulfate dissolve.

#### daveshorts

• Moderator
• Neilep Level Member
• Posts: 2583
• Physics, Experiments
##### Re: Diference between "cupering" proces
« Reply #3 on: 16/08/2007 15:53:46 »
Also once the copper has covered the iron the iron can't get at the solution so the reaction will stop,  so if you want any thickness of copper you will need to electroplate it.

#### Bored chemist

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##### Diference between "cupering" proces
« Reply #4 on: 16/08/2007 18:14:59 »
Process A works just fine, 15 minutes is plenty of time to copper coat the nail. In this case the energy required to remove the copper from the solution is supplied by the energy released as the nail (iron or zinc) dissolves. Once all the nail is covered up the process stops.

In the second case the enery required to get the copper out of solution comes from the battery. This can continue until the battery goes flat or all the copper anode disolves.

#### lightarrow

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##### Diference between "cupering" proces
« Reply #5 on: 16/08/2007 19:09:28 »
Process A works just fine, 15 minutes is plenty of time to copper coat the nail. In this case the energy required to remove the copper from the solution is supplied by the energy released as the nail (iron or zinc) dissolves. Once all the nail is covered up the process stops.

Yes, the process is not so slow; if then you use Zn instead of Fe, the reaction is much faster, and produces heat; the Zn is continuously dissolved from Cu++ and at the end you find no Zn and Cu powder at the bottom of the container.

The copper layer on the Fe is not very compact, however, it crumbs quite easily. In the second case, I wonder why the use of H2SO4 (I don't think it's to help CuSO4 dissolution, in case it's the opposite). Maybe it's to keep in solution Fe++ and Fe+++ formed in the reaction.
« Last Edit: 16/08/2007 19:12:45 by lightarrow »

#### The Naked Scientists Forum

##### Diference between "cupering" proces
« Reply #5 on: 16/08/2007 19:09:28 »