Nitric Acid Acts Upon Copper

Revised 052412

While reading a textbook of chemistry I While reading a textbook of chemistry I came upon the statement, "nitric acid acts came upon the statement, "nitric acid acts upon copper." I was getting tired of upon copper." I was getting tired of reading such absurd stuff and I was reading such absurd stuff and I was determined to see what this meant. determined to see what this meant. Copper was more or less familiar to me, Copper was more or less familiar to me, for copper cents were then in use. I had for copper cents were then in use. I had seen a bottle marked nitric acid on a table seen a bottle marked nitric acid on a table in the doctor's office where I was then in the doctor's office where I was then "doing time.""doing time."

I did not know its peculiarities, but the I did not know its peculiarities, but the spirit of adventure was upon me. Having spirit of adventure was upon me. Having nitric acid and copper, I had only to learn nitric acid and copper, I had only to learn what the words "act upon" meant. The what the words "act upon" meant. The statement "nitric acid acts upon copper" statement "nitric acid acts upon copper" would be more than mere words.would be more than mere words.

All was still. In the interest of knowledge All was still. In the interest of knowledge I was even willing to sacrifice one of the I was even willing to sacrifice one of the few copper cents then in my possession. I few copper cents then in my possession. I put one of them on the table, opened the put one of them on the table, opened the bottle marked nitric acid, poured some of bottle marked nitric acid, poured some of the liquid on the copper and prepared to the liquid on the copper and prepared to make an observation. But what was this make an observation. But what was this wonderful thing which I beheld?wonderful thing which I beheld?

The cent was already changed and it was The cent was already changed and it was no small change either. A green-blue no small change either. A green-blue liquid foamed and fumed over the cent liquid foamed and fumed over the cent and over the table. The air in the and over the table. The air in the neighborhood of the performance became neighborhood of the performance became colored dark red. A great colored cloud colored dark red. A great colored cloud arose. This was disagreeable and arose. This was disagreeable and suffocating. How should I stop this?suffocating. How should I stop this?

I tried to get rid of the objectionable mess I tried to get rid of the objectionable mess by picking it up and throwing it out of the by picking it up and throwing it out of the window. I learned another fact. Nitric window. I learned another fact. Nitric acid not only acts upon copper, but it acts acid not only acts upon copper, but it acts upon fingers. The pain led to another upon fingers. The pain led to another unpremeditated experiment. I drew my unpremeditated experiment. I drew my fingers across my trousers and another fingers across my trousers and another fact was discovered. Nitric acid acts upon fact was discovered. Nitric acid acts upon trousers. trousers.

Taking everything into consideration, Taking everything into consideration, that was the most impressive experiment that was the most impressive experiment and relatively probably the most costly and relatively probably the most costly experiment I have ever performed... It experiment I have ever performed... It was a revelation to me. It resulted in a was a revelation to me. It resulted in a desire on my part to learn more about desire on my part to learn more about that remarkable kind of action. Plainly, that remarkable kind of action. Plainly, the only way to learn about it was to see the only way to learn about it was to see its results, to experiment, to work in a its results, to experiment, to work in a laboratory.laboratory. Ira RemsenIra Remsen

Ira Remsen, born in New York City in Ira Remsen, born in New York City in 1846, was originally trained as a 1846, was originally trained as a medical doctor but left that field to study medical doctor but left that field to study chemistry and went on to become a chemistry and went on to become a leader in chemical education and leader in chemical education and research and to become the president of research and to become the president of Johns Hopkins University. He was the Johns Hopkins University. He was the accidental discoverer of saccharin, an accidental discoverer of saccharin, an artificial sweetener.artificial sweetener.

In this lab you will be following In this lab you will be following copper through a series of steps copper through a series of steps called the …called the …

The The Copper Copper CycleCycle

The The Copper Copper CycleCycle

A series of reactions A series of reactions involving copper involving copper

where the products where the products from one step become from one step become the reactants for the the reactants for the

next step.next step.

The major drawback to The major drawback to this experiment is the first this experiment is the first step.step. The reaction that The reaction that

Ira Remsen described.Ira Remsen described.

The reaction where nitric The reaction where nitric acid acts upon copper.acid acts upon copper.

The nitric The nitric acid itself acid itself

is dangerous.is dangerous.

The brown gas is toxic.

Use a fume hood!

The brown gas is toxic.

Place several copper pennies in a 250 mL Place several copper pennies in a 250 mL beaker and add concentrated nitric acid, beaker and add concentrated nitric acid, HNOHNO33. This must be done in a hood, . This must be done in a hood,

preferably by your instructor.preferably by your instructor.

Step 1 Step 1

Hazards: HNOHazards: HNO33 or NO or NO22 should not be should not be

allowed to touch your skin or eyes. It allowed to touch your skin or eyes. It should be washed off immediately. should be washed off immediately. Do not breathe the brown gas. Do not breathe the brown gas.

Step 1 Step 1 Place several copper pennies in a 250 mL Place several copper pennies in a 250 mL beaker and add concentrated nitric acid, beaker and add concentrated nitric acid, HNOHNO33. This must be done in a hood, . This must be done in a hood,

preferably by your instructor.preferably by your instructor.

Hazards: HNOHazards: HNO33 or NO or NO22 should not be should not be

allowed to touch your skin or eyes. It allowed to touch your skin or eyes. It should be washed off immediately. should be washed off immediately. Do not breathe the brown gas. Do not breathe the brown gas.

Look for the indicators of a chemical reaction.

Formation of a gas or a precipitate, a temperature change, or a color change.

The 18M stock The 18M stock solution of solution of nitric acid.nitric acid.

A 4M solution of A 4M solution of nitric acid.nitric acid.

Copper pennies.Copper pennies.

The pennies are The pennies are placed into a placed into a beaker of nitric beaker of nitric acid, HNOacid, HNO33, in a , in a

fume hood.fume hood.

A watch glass A watch glass makes the gas makes the gas more visible.more visible.

Check out the Check out the temperature temperature change.change.

What changes What changes do you observe do you observe in the liquid?in the liquid?

This sample This sample went from went from

22C to 38C.22C to 38C.

Is the reaction Is the reaction exothermic or exothermic or endothermic?endothermic?

The reaction is The reaction is stopped by stopped by removing the removing the pennies..pennies..

What changes What changes do you observe do you observe in the pennies?in the pennies?

How has the How has the liquid phase liquid phase changed?changed?

With what With what acids will acids will copper react?copper react?

What accounts What accounts for the color?for the color?

The pennies The pennies used must used must have been have been minted before minted before 1982.1982.

Why?Why?

Step 2 Step 2

Add about 10 mL of the solution from Step 1 Add about 10 mL of the solution from Step 1 to a 250mL beaker. Float the beaker in water to a 250mL beaker. Float the beaker in water in a 400 mL beaker. in a 400 mL beaker.

Hazards: The copper solution contains Hazards: The copper solution contains nitric acid. It should be washed off nitric acid. It should be washed off immediately.immediately.

This makes a constant temperature water bath.This makes a constant temperature water bath.

Step 2 Step 2

Add 20mL of sodium hydroxide, NaOH, and, Add 20mL of sodium hydroxide, NaOH, and, if necessary, continue to add NaOH in 10mL if necessary, continue to add NaOH in 10mL increments until the solution is basic to litmus. increments until the solution is basic to litmus.

Hazards: NaOH should not be Hazards: NaOH should not be allowed to touch your skin or eyes. It allowed to touch your skin or eyes. It should be washed off immediately.should be washed off immediately.

Litmus is red in an acid, blue in a base.

Step 3 Step 3 Add 50 mL of water to the 250 mL beaker Add 50 mL of water to the 250 mL beaker and place on a hot plate at low heat. Do and place on a hot plate at low heat. Do notnot bring the water to a boil. Continue heating bring the water to a boil. Continue heating with stirring until the change is complete. with stirring until the change is complete. Work any blue solid on the sides of the Work any blue solid on the sides of the beaker into water with a stirring rod. beaker into water with a stirring rod. Remove the beaker from the hot plate and Remove the beaker from the hot plate and allow the liquid to cool.allow the liquid to cool.

Hazards: Do not allow the hot contents to splatter.

When the reaction is complete, it is When the reaction is complete, it is necessary to wash the product.necessary to wash the product.

Allow the solid to settle. Allow the solid to settle. Then decant the clear Then decant the clear solution. Add 50 mL of solution. Add 50 mL of water and stir. When the water and stir. When the solid has settled, decant the solid has settled, decant the clear solution. clear solution.

What is being What is being removed by removed by the washing the washing process?process?

Step 3 Step 3

Add about 50 mL of 3.0M sulfuric acid, Add about 50 mL of 3.0M sulfuric acid, HH22SOSO44, with stirring to the 250 mL beaker. , with stirring to the 250 mL beaker.

Add enough acid for a complete change. Add enough acid for a complete change.

Hazards: Sulfuric acid should not be Hazards: Sulfuric acid should not be allowed to touch your skin or eyes. It allowed to touch your skin or eyes. It should be washed off immediately.should be washed off immediately.

Step 4 Step 4

Use the stirring rod to work all of the solid off Use the stirring rod to work all of the solid off the walls of the beaker and into the liquid.the walls of the beaker and into the liquid.

Add 6 to 7 grams of zinc metal (Zn) to Add 6 to 7 grams of zinc metal (Zn) to the beaker.the beaker.

Hazards: The sulfuric acid already in Hazards: The sulfuric acid already in the beaker.the beaker.

Do not stir, it’s Do not stir, it’s more interesting if more interesting if you don’t.you don’t.

Step 5 Step 5

The complete The complete reaction will take reaction will take a while, so please a while, so please be patient.be patient.

Copper Lab

Balancing EquationsEvidence of

reaction

Types of reactions

Predicting products

Acid/base neutralization

Net ionic equations

REDOX

Reaction rate factors

pH and [H+]

Stoichiometry

Activity series

Solubility rules

Acids

Stock system

Nomenclature

1. Precipitate2. Gas given off3. Temperature change4. Color change

1. Synthesis2. Decomposition3. Single replacement4. Double replacement5. Combustion of a hydrocarbon

1. Concentration2. Temperature3. Surface area4. Catalyst

Thermodynamics Endothermic & exothermic

Reaction pathway diagramsActivation energy

Oxidizing and reducing agents

Strong & weak

The Copper Cycle LabThe Copper Cycle Lab

Comments or questions may be directed to

Mike JonesPisgah High School

Canton NC

mjones@haywood.k12.nc.us

NC DPI Science Leadership Conference07/13/05