Use chemistry to remove the copper plating on a penny

Use chemistry to remove the copper plating on a penny
YouTube user zbret...
3Ca(OH)2 + 4S -- 2CaS + CaS2O3+ 3H2O This liquid is known as Lime Sulfur and is made the same way - a surfactant plus Sulfur plus Calcium Hydroxide, all boiled for several minutes.

The reaction with copper:
CaS2O3 + 4Cu + H2O -- 4CuO + CaS + H2S

Or combined:
3Cu + 2Ca(OH2) +3S -- 3CuO + 2CaS + H2S + H2O

The new liquid reacts with copper:
2CaS + H2S + 3Cu -- 3CuO + H2O

Zinc is not attacked by calcium hydroxide (or by anything else here).

Category:

Science & Technology

Tags:

• Copper
• penny
• chemistry
• penny chemistry
• copper removal
• silver Penny
• zinc penny
• sulfur
• calcium hydroxide
• interesting chemistry
• fun chemistry

[taylorlenz]

I was super excited to do this for my chemistry class. But, when I followed your directions exactly it did not work out as you stated. Yes, within seconds a black copper sulfide layer formed on the penny. But, when I left it in the boiling solution for 15 minutes and returned to check it was completely dissolved. Only little black specks were found at the bottom. When I let it settle, a reddish liquid layer on top of the yellowish precipitation on the bottom. That must be Cuprite CuO

[myst32YT]

@taylorlenz Sorry about that. If you can, try it again but will less time. With everyone using different setups and chemical purity it can be difficult to reproduce results. I had to leave them in for 15 min but you may be using better chemicals than I and need only 5 min..

[myst32YT]

No... it would attack the silver...

[myst32YT]

@blackjet84 They are regular copper plated zinc pennies... Nothing formed reacts with zinc thus zinc is not attacked.

[myst32YT]

No it is zinc..

YouTube user zbret figured it out...

3Ca(OH)2 + 4S -- 2CaS + CaS2O3+ 3H2O

The reaction with copper:

CaS2O3 + 4Cu + H2O -- 4CuO + CaS + H2S

Or combined:

3Cu + 2Ca(OH2) +3S -- 3CuO + 2CaS + H2S + H2O

The new liquid reacts with copper:

2CaS + H2S + 3Cu -- 3CuO + H2O

Zinc is not attacked by calcium hydroxide (or by anything else here).

[maxx1231]

can you use sodium hydroxide instead of calcium hydroxide?

[myst32YT]

@maxx1231 Will have to try it... I don't think it will work but can't say that for sure.. Will try.... and let you know..

[SaveMeSteak]

sorry i got thirsty that looked so good

[xexorz]

@myst32YT What year penny did you use? Pennies before 1982 were 100% copper. Post 1982 are the zinc/copper plated type. About 50% from 1982 are copper and the other half are plated.

[japanesepoptart]

@yellowmetalcyborg

Then maybe parrafin and sulfur is a good way to do it. Like I said though, I'm not entirely sure what the purity of the product will be...

[yellowmetalcyborg]

@japanesepoptart It's not that I need H2S, it's just that H2S is a useful gas. It can be used to make thiols, metal sulfides, analytical reagents and is in some cases used as a reducing agent in chemical reactions. I make H2S by reacting Al2S3 with water, but the aluminium sulfide is difficult to make and the process is time consuming. I'm working on a way to make large quantities of H2S cheaply via the reduction of sulphate by sulphate reducing bacteria, but I'm not quite done yet.

[japanesepoptart]

@yellowmetalcyborg

I remember being able to generate hydrogen sulfide by heating sulfur with parrafin (candle wax).

Not sure how pure it would be though. Also, Just curious but, why would you need hydrogen sulfide?

[sivalley]

@myst32YT Substituting Ca(OH)2 for NaOH will not work. Due to Na+'s higher electronegative potential it will not attack the Cu clad, but it will attack the Zn core if the clad is punctured. You'll end up with a very slow scavenging reaction that is thermally dependent as Zn(OH)2 balances with NaOH. Cooler solutions will have a higher Na+ activity, where hotter ones will have a higher Zn+2 activity.

[yellowmetalcyborg]

Did you smell rotten eggs before you put the pennies into this mix? I was wondering if this was a reliable way to make a hydrogen sulphide gas generator. Setting the copper aside, the two chemicals react to form both CaS and CaS2O3. Ignoring the CaS2O3, the sulfide salt reacts with water to form H2S gas and calcium hydroxide that can be recycled and reacted with more sulfur.

So would this be a H2S generator if the S was in massive excess?

Your last reaction isn't balanced

Just pointing it out...

[zerosix1786]

why would we drink it? lol