Use chemistry to remove the copper plating on a penny

[K333N3R]

I think its more likely that the S2O3(2-) ion created by reaction of Ca(OH)2 and S is reacting with the Cu surfacing. Its highly unlikely for the CaS crystal structure to react with the coin. It also seems unlikely that the H2S (gas) or H+ (aqueous) to be adequate to oxidise the Cu. The S2O3(2-) probably reacts with the Cu by donating an electron, filling the 4s2 orbital which is vacant in Cu, but not vacant in the zinc.. This seems more likely.. Btw, wear nitrile gloves, latex arent good enough

[SaveMeSteak]

sorry i got thirsty that looked so good

[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..

[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.

[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...

[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?

[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

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...

[zerosix1786]

why would we drink it? lol

[purplemutantas]

That's way cool! 

[hunterboyvids]

Take copper sulfate and baking soda to get copper carbonate then add peroxide to and watch it go different colors

[bears7777777]

wait! how can you drink fumes. lol

[hcoaf789]

Is there a way to collect the copper from the zinc pennies?

[8DuncanConstruction8]

@hcoaf789 i wanted to know the same thing....

[myst32YT]

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

[kame25]

would this work on a rhodium plated silver ring?

[myst32YT]

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

[sk8terbeginner91]

so you turned a penny into silver by removing the copper plating, but will it attach to a magnet

[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).

[moctezuma112]

@myst32YT

hello,

i have 10 rolls of pennies 1930-1982 (95% copper; 5% zinc)

i know nitric acid dissolves copper and gives dangerous fumes.

i saw another video that Hydrochloric acid dissolves zinc, gives out fumes but less dangerous.

so my question is: will it be easier if can i use hydrochloric acid to remove the 5% zinc out of 1909-1982 pennies to make it 99.9% copper for smelting?

thanx =)

[blackjet84]

@moctezuma112

this is what i would like to know. if you find out shoot me an e-mail.

[blackjet84]

@moctezuma11 this is what i would like to know, shoot me an e-mail if you find out how.

[AuraRisen]

Are you sure it is zinc, and not stainless steel? because copper is more "noble" than zinc, then if you have copper ions the copper ions will oxidize zinc to zinc ions e reduce the copper! Please tell what you think about this!

[yellowmetalcyborg]

Genius!

I shall use this method for making zinc electrodes for zinc air batteries.

Thank you for posting a video of something that has never been done before.

[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..

[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.

[hobomnky]

awsome!!

[starshock01]

hydroxide catalyzed copper to start oxidation, copper oxide changed with sulfur, since copper more readily gives up a valence electron it dissolves way before zinc, but thats a tad bit scary how easy it is to make hydrogen sulfide...

[ThereWasThisOneTime]

Did you look under a microscope to check that Zinc oxide wasnʻt forming? That would have protected it from further oxidation.

[AHW214]

Do you think enough hydrogen sulfide was produced to seriously hurt someone even when preformed outside because I have all the chemicals and supplies to preform this but the H2S makes me pretty nervous.

[myst32YT]

@AHW214 Only a very small amount is made... doing this outside will be fine.

[myst32YT]

@AHW214 Not enough to hardly notice... outside will be fine..

[zbret]

I believe I have it:

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)

[spotlightman1234]

i have been trying to find this for my whole life thank you!!!!! i cant thank you enough!!!!!!!!! i thought the only way was with cyanide compounds !! how can i return the favor?

[AHW214]

Awesome video!

Do you think you could remove the copper shell by putting the penny in just enough nitric acid to react the copper off but by the time the copper is gone, the nitric acid has fully reacted. The copper nitrate made would deposit copper on the zinc, but this could be washed off.

[myst32YT]

@AHW214 The acid does not dissolve evenly. I tried this once and it does work but the zinc was pitted.

[flavocachata]

Really enjoyed it!

I'm curious to know why didn't the zinc get attacked.

[hkparker]

Awesome video, I didn't think dissolving only the copper would be easy. As far as whats going on in the reaction I know that copper sulfide is black, so im assuming thats what forms on the copper metal. Not sure why it wouldnt form on the zinc, or why the copper hydroxide is there. Perhaps the hydroxide acts as a catalyst, or maybe to prevent the sulfur from reacting with the zinc.

[Kendrana]

@hkparker Well, I remember having read that zinc only reacts with sulphur to form ZnS if you ignite the two compounds together, and since you're not really burning anything, that might be why it isn't forming?

Still doesn't explain why you need the Ca(OH)2 but that's part of the puzzle.

[hkparker]

@Kendrana yea, thats why I was thinking catalyst, but i kinda doubt you would need that much then

[zbret]

You comment about toxic vapors coming from this, any idea what they are? H2S? SO2? Perhaps there is a clue there?

[myst32YT]

@zbret H2S is coming off...

[mewrox99]

@myst32YT

Yeah, the sulfur dissolves in water at an extremely high pH to form a polysulfide solution. When heated it hydrolysis to H2S.

[Kendrana]

Great stuff! It's interesting, I wonder what's going on too!