A learning experience

[hermanntrude]

I was browsing the internet and came upon this fantastic quote from Ira Remsen:

 

While reading a textbook of chemistry I came upon the statement, "nitric acid acts upon copper." I was getting tired of reading such absurd stuff and I was 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 doctor's office where I was then "doing time." I did not know its peculiarities, but the spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words "act upon" meant. 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 green-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 colored 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 of the window. 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. . . . 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.

 

source

[Kaeroll]

I recently read this passage in a (short) book on the history of chemistry. It struck me as very true to the spirit of science.

[Theophrastus]

While it may seem hilarious to the author in retrospect, I do not think that this is an experiment I desire to replicate. Personally, I recently read a book of a similar nature, absolutely brilliant, Oliver Sacks', "Uncle Tungsten: memories of a chemistry boyhood" It really quite a wonderful book. Interesting quote, however, is there any underlying truth to this, as it is true as the author states, that theoretically nitric acid does not react with pure copper. Perhaps it was some manner of oxidised layer of oxide, carbonate, hydroxide etc, and I do know that many coins, currently, only have a thin electroplated layer of copper on top, under which rests a cheaper metal, or metal alloy, generally of iron, nickel and zinc, in various proportions. Any thoughts?

[max.yevs]

oh, theo, nitric acid does react with copper, quite violently i might add...

 

it seems like it would not because copper generally does not react with acids, but nitric acid is no usual acid- it usually is not even willing to liberate its hydrogen.

 

[ce]Cu + 4HNO3 -> Cu(NO3)2 + 2NO2 + 2H2O[/ce]

 

and apparently [ce]NO2[/ce] is very toxic

 

i've never handled nitric acid, but here's a video

[Theophrastus]

Really? Cool! I've never really done anything with it, and know it far worse than most other common acids. Interesting...

[hermanntrude]

theo, Uncle tungsten is my favourite book in the world.

 

Max is correct in that the "[ce]H+[/ce]" part of [ce]HNO3[/ce] doesn't react with copper, but the [ce]NO3-[/ce] surely does. My students did the reaction the other day in the fume hoods. It's a very violent reaction which gives off copious quantities of both heat and very nasty gases. At lower concentrations of acid you get NO instead of NO2.

[max.yevs]

yeah, nitric acid works on a whole different level then most acids... supposedly only in cold alkalis/alkali earth metals it will liberate its hydrogen..

 

although I suppose with a base it would probably react as expected- i.e.

[ce]NaOH + HNO3 > H2O + NaNO3[/ce]

 

and doesn't NO quickly oxidize in air to NO2 hermann? So my bet is that its not much safer then NO2