Nitric Acid Acts Upon Copper
Revised 052412
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.
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.
Ira Remsen
Ira Remsen, born in New York City in
1846, was originally trained as a
medical doctor but left that field to study
chemistry and went on to become a
leader in chemical education and
research and to become the president of
Johns Hopkins University. He was the
accidental discoverer of saccharin, an
artificial sweetener.
In this lab you will be following
copper through a series of steps
called the …
The
Copper
Cycle
The
Copper
Cycle
A series of reactions
involving copper
where the products
from one step become
the reactants for the
next step.
The major drawback to
this experiment is the first
step.
The reaction that
Ira Remsen described.
The reaction where nitric
acid acts upon copper.
The brown
gas is toxic.
The nitric
acid itself
is dangerous.
The brown
gas is toxic.
Use a
fume hood!
Step 1
Place several copper pennies in a 250 mL
beaker and add concentrated nitric acid,
HNO3. This must be done in a hood,
preferably by your instructor.
Hazards: HNO3 or NO2 should not be
allowed to touch your skin or eyes. It
should be washed off immediately.
Do not breathe the brown gas.
Step 1
Place several copper pennies in a 250 mL
beaker and add concentrated nitric acid,
HNO3. This must be done in a hood,
preferably by your instructor.
Look for the indicators of a chemical reaction.
Formation of a gas or a precipitate,
a temperature change, or a color change.
Hazards: HNO3 or NO2 should not be
allowed to touch your skin or eyes. It
should be washed off immediately.
Do not breathe the brown gas.
The 18M stock
solution of
nitric acid.
A 4M solution of
nitric acid.
Copper pennies.
The pennies are
placed into a
beaker of nitric
acid, HNO3, in
a fume hood.
A watch glass
makes the gas
more visible.
What changes
do you observe
in the liquid?
Check out the
temperature
change.
This sample
went from
22C to 38C.
Is the reaction
exothermic or
endothermic?
The reaction is
stopped by
removing the
pennies..
What changes
do you observe
in the pennies?
How has the
liquid phase
changed?
What accounts
for the color?
With what
acids will
copper react?
The pennies
used must
have been
minted before
1982.
Why?
Step 2
Add about 10 mL of the solution from Step 1
to a 250mL beaker. Float the beaker in water
in a 400 mL beaker.
This makes a constant temperature water bath.
Hazards: The copper solution contains
nitric acid. It should be washed off
immediately.
Step 2
Add 20mL of sodium hydroxide, NaOH, and,
if necessary, continue to add NaOH in 10mL
increments until the solution is basic to litmus.
Litmus is red in an acid, blue in a base.
Hazards: NaOH should not be
allowed to touch your skin or eyes. It
should be washed off immediately.
Step 3
Add 50 mL of water to the 250 mL beaker
and place on a hot plate at low heat. Do not
bring the water to a boil. Continue heating
with stirring until the change is complete.
Work any blue solid on the sides of the
beaker into water with a stirring rod.
Remove the beaker from the hot plate and
allow the liquid to cool.
Hazards: Do not allow the hot
contents to splatter.
Step 3
When the reaction is complete, it is
necessary to wash the product.
Allow the solid to settle.
Then decant the clear
solution. Add 50 mL of
water and stir. When the
solid has settled, decant the
clear solution.
What is being
removed by
the washing
process?
Step 4
Add about 50 mL of 3.0M sulfuric acid,
H2SO4, with stirring to the 250 mL beaker.
Add enough acid for a complete change.
Use the stirring rod to work all of the solid off
the walls of the beaker and into the liquid.
Hazards: Sulfuric acid should not be
allowed to touch your skin or eyes. It
should be washed off immediately.
Step 5
Add 6 to 7 grams of zinc metal (Zn) to
the beaker.
The complete
Do not stir, it’s
reaction will take
more interesting if
a while, so please
you don’t.
be patient.
Hazards: The sulfuric acid already in
the beaker.
Oxidizing and reducing agents
The Copper Cycle Lab
Activity
series
REDOX
Solubility
rules
1. Synthesis
2. Decomposition
3. Single replacement
4. Double replacement
5. Combustion of a
hydrocarbon
1. Precipitate
2. Gas given off
3. Temperature change
4. Color change
Predicting products
Types of reactions
Evidence of
reaction
Balancing Equations
Copper Lab
Net ionic
equations
Stock system
Nomenclature
Acids
Stoichiometry
Acid/base neutralization
Reaction rate
factors
1. Concentration
2. Temperature
3. Surface area
4. Catalyst
pH and [H+]
Strong & weak
Thermodynamic
s
Activation energy
Endothermic & exothermic
Reaction pathway
Comments or questions may be directed to
Mike Jones
Pisgah High School
Canton NC
mjones@haywood.k12.nc.us
NC DPI Science Leadership Conference
07/13/05