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Nitric Acid Acts Upon Copper. Revised 052412.

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Presentation Transcript
slide2

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."

slide3

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.

slide4

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?

slide5

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?

slide6

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.

slide7

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

slide8

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.

slide11

A series of reactions involving copper where the products from one step become the reactants for the next step.

slide12

The major drawback to this experiment is the first step.

The reaction that

Ira Remsen described.

The reaction where nitric acid acts upon copper.

slide13

The brown gas is toxic.

The nitric acid itself

is dangerous.

slide14

The brown gas is toxic.

Use a

fume hood!

slide15

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.

slide16

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.

Look for the indicators of a chemical reaction.

Formation of a gas or a precipitate,

a temperature change, or a color change.

slide17

The 18M stock solution of nitric acid.

A 4M solution of nitric acid.

Copper pennies.

slide18

The pennies are placed into a beaker of nitric acid, HNO3, in a fume hood.

A watch glass makes the gas more visible.

slide19

What changes do you observe in the liquid?

Check out the temperature change.

slide20

This sample went from 22C to 38C.

Is the reaction exothermic or endothermic?

slide21

The reaction is stopped by removing the pennies..

What changes do you observe in the pennies?

slide22

How has the liquid phase changed?

What accounts for the color?

With what acids will copper react?

slide24

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.

slide25

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.

slide26

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.

slide27

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?

slide28

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.

slide29

Step 5

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

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

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

Hazards: The sulfuric acid already in the beaker.

slide30

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

Stock system

Net ionic equations

Nomenclature

Acids

Stoichiometry

Acid/base neutralization

Reaction rate factors

pH and [H+]

1. Concentration

2. Temperature

3. Surface area

4. Catalyst

Strong & weak

Thermodynamics

Endothermic & exothermic

Activation energy

Reaction pathway diagrams

slide31

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