In this demo, students will hear a story about how Ira Remsen’s interest in chemistry was sparked and watch a demonstration that recreates her first experiment reacting nitric acid with a copper penny.
By the end of this lesson, students should be able to
- explain how Ira Remsen’s interest in chemistry was sparked.
- explain the steps in the reaction between copper and nitric acid.
This lesson supports students’ understanding of
- History of chemistry
- Chemical changes
- Redox reaction
Teacher Preparation: 1 hour
Lesson: 20 minutes
- Concentrated nitric acid
- 1-L Erlenmeyer flask
- One-hole stopper that fits on the Erlenmeyer flask
- Polished glass tubing that fits into the hole stopper
- Clear plastic hose that fits over the glass tubing
- Piece of copper
- 2-L beaker
- Fume hood
- Safety goggles
- This experiment should be done in a fume hood, as toxic gas is released.
- Wear an apron, gloves, and safety goggles while performing the demonstration.
- Take extreme care when handling concentrated nitric acid.
- This demonstration can be used to start off the year, sparking student interest in chemistry and a desire to learn an explanation of all of the things that happened before their eyes.
- This demonstration will produce a two-step reaction between copper and nitric acid.
Secure a short piece of polished glass tubing through a one-hole stopper. Fit the stopper into the top of a one-liter Erlenmeyer flask. Attach one end of a length of clear plastic hose to the glass tubing and place the other end in a two-liter beaker that is filled with water. Cut a two cm square of copper. (It will represent Remsen’s penny.) Have 50 mL of concentrated nitric acid. This should be placed in your fume hood. Wear an apron and safety goggles while performing the demonstration.
Read the following story by Ira Remsen, who discovered saccharin and founded the department of chemistry at Johns Hopkins University.
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 more than mere words.
Hold up the nitric acid and copper when they are mentioned. Place the copper in the flask. Continue reading the autobiography.
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?
Pour the nitric acid into the flask after reading the second sentence and quickly tighten the stopper. Continue to slowly read the autobiography as the reaction occurs.
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.
Point out how the brown gas ‘disappeared’ as it bubbled through the water. Allow the second reaction to occur, which will take place as the copper(II) nitrate cools. The water will be drawn into the flask, making the brown gas disappear and the green liquid turn blue.