Instructables

Demonstrating Nitric Acid Acts Upon A Copper Penny Experiment

video Demonstrating Nitric Acid Acts Upon A Copper Penny Experiment
AKA-Penny Operated Nitric Acid Fountain Nitric acid acts upon copper to yield nitric oxide in an exothermic reaction. The expanding gas displaces water from another flask; actually bubbles in this set up. When the gas cools, the water is drawn back into the flask, dissolving the nitric oxide and forming a blue solution with the copper ions still there. Very cool reaction.

Equipment:

500 mL florence flask
ring stand
large ring placed below the flask
small ring that fits over the neck of the flask
one-hole rubber stopper
60 cm glass tubing
large container of water

The glass tube is bent in such a way as to connect the top of the flask with the bottom of the water container. The water in the container can be stirred by hand or with a magnetic stirrer. It needs to be stirred, however, or else the NO2 gas collects above the liquid.

Safety and Disposal
The solution is highly acidic. I pour it out into a large beaker or battery jar and add excess sodium carbonate. The carbon dioxide bubbles indicate neutralization and the resulting copper carbonate precipitate is filtered, placed in a baggie and thrown away. The neutralized filtrate can be disposed of as you would any simple salt solution. Procedures may vary from location to location.

Nice Reading While Doing this Experiment-
While reading a text book of chemistry, I came upon the statement, "nitric acid acts upon copper." I was getting tired of reading such absurd stuff and I determined to see what this meant. Copper was more or less familiar to me, for copper cents were then in use. I had seen a bottle marked "nitric acid" on a table in the doctors office where I was then 'doing time'! I did not know its peculiarities, but I was getting on and likely to learn. The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words "act upon" meant. Then the statement "nitric acid acts upon copper", would be something more than mere words. All was still. In the interest of knowledge I was even willing to sacrifice one of the few copper cents then in my possession. I put one of them on the table; opened the bottle marked "nitric acid"; poured some of the liquid on the copper; and prepared to make an observation. But what was this wonderful thing which I beheld? The cent was already changed, and it was no small change either. A greenish blue liquid foamed and fumed over the cent and over the table. The air in the neighborhood of the performance became colored dark red. A great cloud arose: This was disagreeable and suffocating--how should I stop this? I tried to get rid of the objectionable mess by picking it up and throwing it out the window, which I had meanwhile opened. I learned another fact--nitric acid not only acts upon copper but it acts upon fingers. The pain led to another unpremeditated experiment. I drew my fingers across my trousers and another fact was discovered. Nitric acid acts upon trousers. Taking everything into consideration, that was the most impressive experiment, and, relatively, probably the most costly experiment I have ever performed. I tell of it even now with interest. It was a revelation to me. It resulted in a desire on my part to learn more about that remarkable kind of action. Plainly the only way to learn about it was to see its results, to experiment, to work in a laboratory.
-- Ira Remsen (1846-1927)

The Chemistry...
Oxidation of copper metal with a strong oxidizing agent, conc. nitric acid.
In a classic experiment, copper metal is turned into copper(II) ion while the nitrogen(V) in the nitrate ion becomes nitrogen(IV) in the nitrogen dioxide gas.

Charles' Law
As the temperature from the reaction warms the gas, it expands. Later, as it cools, the gas contracts.

Nonmetal oxides are acid anhydrides (also link to acid rain)
Although the nitrogen dioxide gas is noxious and toxic, it dissolves readily in water and make the solution acidic. This can be shown by adding a little indicator to the water and making the water slightly basic before the copper is added to the acid.

Air pressure
As the pressure in the flask is decreased as it cools, the outside pressure pushes the water up the tubing toward the flask. The nitrogen dioxide gas is not pulling the water in.

Descriptive chemistry--copper solutions are green and blue
The colored solutions come from complexes of copper(II) ion in solution. Aqueous copper ion is blue, Cu(H2O)42+ The green must be copper surrounded by nitrates.

Reference-http://www.chemmybear.com/demo.htm
fishguycpf5 months ago

I can speak of the toxic effects of Cu in HNO3. My advice is never every let the two mix. One of my students did it in my chemistry class and left it on my desk in my office as a present. I was out for a while and it felt like somebody took a cheese grater to my throat and lungs. I don't even mention this reaction anymore.

Valche6 years ago
It should be noted here that the nitrogen dioxide gas being produced here is highly toxic.
ok now on the note of toxic chemicals what gas did i just produce when i started melting sugar and salt peter and or stump remover????!?!?!?! cause i got a big whiff and i about passed out!
Okay, well first of all why the hell would you mix stump remover in there?? Not only are the initial fumes from the salt peter and sugar not good for you, but stump remover contains sodium hydroxide and is extremely caustic. I couldn't tell you what gases you may have produced, but I'm sure that even vaporizing one of those chemicals is terrible in the first place.
___ Valche5 years ago
not all stump remover
conrad2468 ___5 years ago
It was AMMONIUM nitrate instead of POTASSIUM nitrate! AH!
i was making a smoke bomb
I'm aware of that, sodium hydroxide (the stump remover) is not a typical ingredient in smoke bombs. I can't foresee any reason to include that in there.
BOXHARD Valche6 years ago
If you were using the brand "Stump Out" it's 99.8% potassium nitrate... I ran it on a GC... As for the fumes, (if it was more or less pure KNO3... and let me note that from the sounds of it it wasn't, then there should not have been any fumes what so ever... Lesson... go to the Ag store and just buy ag quality (90% or less) potassium nitrate, or go to the drug store and get 99.99% KNO3 in tiny bottles that are way over priced, OR ORDER IT ON-LINE FROM a chemistry / pyro site that has decent prices.
The actual ingredient in stump remover is saltpetre. The NaOH is one of the impurities, meaning it is <%2 caustic soda.
Hmm actually it mihgt have an effect on the reaction, an interesting one for all we know, but most likely not../.
hmmm well i assumed it contained the ingredient "salt peter"
well thanks for the info i think i lost a couple of qi points
qi points?
Derin Valche6 years ago
i guess he meant iq
yes i do ok let me explain again if i loose iq points im too stupid to to say iq so i said qi to make a point that i lost iq points!
hold yer breath!!!AHHHHHH!!(dropped florence flask)
Hahaha
I got a question here.Is it the copper coating or the zinc inside?
dasgemuse5 years ago
it would be better if the video would slow down to normal when the guy was talking, because i feel thatwhat he had to say would be more informative than the text. all in all a good video. can nitric acid be made with ammonium sulphate?or just AN and also KNO3?
The "nitrate" ion is what is used to make nitric acid -just as sulfate salt would be used in sulfuric acid production.
knoxarama5 years ago
i have a theory. try cutting a slit in the penny, then put it in the acid. the zinc and copper from the penny will conduct a charge, then short curcuit one its self. or it might not, but it probably will. maybe.
marine123205 years ago
You should've clearly stated that the gas was nitrogen dioxide(well, i think its nitrogen dioxide) and you should've stated the green-blue solution after the reaction is a solution of copper nitrate. Other than that, great video!
bigcheeze6 years ago
does chlorine gas ring a bell?
Chlorine gas isn't being produced here.
OK then, tell me what other gases are greenish brown
Nitrogen dioxide, maybe?
OK,OK,OK,you got me on that one. either or, they are both poisonous
That much is true.
We did this in chemistry yesterday =]