CHEMISTRY CHEMISTRY 8-22-08 Fri (per 1,2,3)8-22-08 Fri (per 1,2,3)WARM-UP:WARM-UP: What is produced in a combustion What is produced in a combustion reaction?reaction?LG: Become familiar with formulas, LG: Become familiar with formulas, subscripts, equations & energy changes.subscripts, equations & energy changes.

TODAY’S AGENDA:TODAY’S AGENDA:TURN IN YOUR ESSAY & CONTRACTTURN IN YOUR ESSAY & CONTRACT1) What Chemical Is It?1) What Chemical Is It?2) Ira Remsen Demonstration2) Ira Remsen Demonstration

HW: HW: Sec 8.2—Read & take notes. Sec 8.2—Read & take notes.

Carbon dioxide (CO2) & water (H2O)

What is produced in a What is produced in a combustion reaction?combustion reaction?

CC66HH1212OO6 6 (s)(s)

formulachemical symbol

(the letter)

subscript(the number)

state symbol

ring standround bottom flask

iron ringpre-1982 penny

clamprubber stopper

tubinggraduated cylinder

To be read during the reaction: 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 pecularities, 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.

To be read during the reaction: 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?

To be read during the reaction: 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.

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Equation for the reaction:Equation for the reaction:

Cu(s) + HNOCu(s) + HNO33(aq) (aq)

NONO22(g) + H(g) + H22O(l) + Cu(NOO(l) + Cu(NO33))22(aq)(aq)

reactants reactants products products

Copper + nitric acid produces

nitrogen + water + copper(II)nitrate dioxide

things on the left things on the right

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State symbolsState symbols

““s” = solids” = solid““l” = liquidl” = liquid““g” = gasg” = gas““aq” = aqueous (dissolved in aq” = aqueous (dissolved in

water)water)

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Energy changesEnergy changes

Because heat is released in Because heat is released in this reaction it is called an this reaction it is called an “exothermic” reaction.“exothermic” reaction.

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Why does the penny have to be Why does the penny have to be “old”?“old”?

Pre-1982 pennies are mostly Pre-1982 pennies are mostly copper.copper.

Post-1982 pennies are made Post-1982 pennies are made up of a zinc core surrounded up of a zinc core surrounded by a thin layer of copper.by a thin layer of copper.

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Chemistry of ColorChemistry of Color

The NOThe NO22 gas produced is gas produced is

brown—ALL COLORED brown—ALL COLORED GASES ARE POISONOUS.GASES ARE POISONOUS.

Copper ions tend to produce Copper ions tend to produce blue solutions.blue solutions.

CHEMISTRY CHEMISTRY 8-22-08 Fri (per 6,7)8-22-08 Fri (per 6,7)WARM-UP:WARM-UP: How do you use a fire How do you use a fire extinguisher, dispose of glass, treat spills?extinguisher, dispose of glass, treat spills?LG: Learn about energy changes & bonds. LG: Learn about energy changes & bonds. Use the scientific method in the lab.Use the scientific method in the lab.

TODAY’S AGENDA: TODAY’S AGENDA: PRIZES!PRIZES!1) Evaluate notes; take Sec. 8.2 quiz.1) Evaluate notes; take Sec. 8.2 quiz.2) Finish Ira Remsen notes.2) Finish Ira Remsen notes.3) Anchor overboard activity.3) Anchor overboard activity.HW: Sec. 1.3—Read & take notes; HW: Sec. 1.3—Read & take notes; NOTE THE CHANGE!!NOTE THE CHANGE!!

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Equation for the reaction:Equation for the reaction:

Cu(s) + HNOCu(s) + HNO33(aq) (aq)

NONO22(g) + H(g) + H22O(l) + Cu(NOO(l) + Cu(NO33))22(aq)(aq)

reactants reactants products products

Copper + nitric acid produces

nitrogen + water + copper(II)nitrate dioxide

things on the left things on the right

17

State symbolsState symbols

““s” = solids” = solid““l” = liquidl” = liquid““g” = gasg” = gas““aq” = aqueous (dissolved in aq” = aqueous (dissolved in

water)water)

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Energy changesEnergy changes

Because heat is released in Because heat is released in this reaction it is called an this reaction it is called an “exothermic” reaction.“exothermic” reaction.

Energy is involved when Energy is involved when bonds between atoms are bonds between atoms are broken and formed.broken and formed.

19

Why does the penny have to be Why does the penny have to be “old”?“old”?

Pre-1982 pennies are mostly Pre-1982 pennies are mostly copper.copper.

Post-1982 pennies are made Post-1982 pennies are made up of a zinc core surrounded up of a zinc core surrounded by a thin layer of copper.by a thin layer of copper.

20

Chemistry of ColorChemistry of Color

The NOThe NO22 gas produced is gas produced is

brown—ALL COLORED brown—ALL COLORED GASES ARE POISONOUS.GASES ARE POISONOUS.

Copper ions tend to produce Copper ions tend to produce blue solutions.blue solutions.