A Chemhistory Lesson Paul D. Price Trinity Valley School pricep@trinityvalleyschoo l.org
ChemHistory
Jun 14, 2015
A ChemHistory Lesson by Paul Price, Trinity Valley School, Texas. This was presented at the ACT2 luncheon on 11/7/09 as part of CAST 2009 in Galveston Texas.
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Transcript
What We Do Is Hard!
• Memorization vs. Understanding• Various Levels of Abstraction• Critical Thinking• Putting it all together
The Use of History
• Puts Discoveries in Context– When?– Why Then?– How?
• The Human Element– I can do this
• Aligns with “Classic” Chem course – 2010 TEKS
The Organizing Principle
• When?
• Who?
• Why Then?
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1913
1813
1803
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Dalton!?
• The mass of atoms?– Needs
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Joseph Black (1728 - 1799)
• Analytical Balance
• Specific + Latent Heat
• Fixed Air (1754)– CaO + CO2 --> CaCO3
– Ca(OH)2 + CO2 --> CaCO3 + H2O
– MgCO3 + HCl --> H2O + CO2 + MgCl2
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Pneumatic Chemistry
• H2 (1766) by Cavendish• O2, HCl, NH3, NO, N2O, SO2 by
Priestley (1774 - 86?)• Cl2 and O2 by Scheele (17??)• Lavoisier (O2 ?)
– Conservation of Mass
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Proust and Dalton
CO
CO2
??
??
??
Nuts and Bolts
Cup 10 is BN. Can you figure out the rest?
Can you explain the data?
• All Matter is made up of indivisible particles called atoms.
• All atoms of the same element are exactly the same; atoms of different elements are different in some fundamental way
• Compounds form when atoms of different elements combine in unique fixed ratio
• In a chemical reaction, atoms are simply rearranged to create new compounds from old
Sample Homework
The Real Payoff
• CO
• One O weighs 1.33 times more!
• Define C = 1, O = 1.33
• Define C = 100 , O =
• Define C = 12, then O = 16133
A Small ProblemCompound Grams of
HydrogenGrams of Oxygen
Possible Formula
?
A 2.000 15.84
B 103.00 815.84
Rule of Greatest Simplicity
OH !
Dalton Mass Table
H = 1
O = 7.92
Gay-Lussac
• 2 vol H + 1 vol O = 2 vol water
• 3 vol H + 1 vol N = 2 vol ammonia
• 1 vol N + 1 vol O = 2 vol nitric oxide
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Diatomics!
Future Developments
• Electrochemistry and diatomic bonding
• Why only H2? (not Hn)
• Organic Chemistry and Empirical vs. Molecular Formula
• Excellent Atomic Weights (Cannizzaro)
Periodic Table
• 6.02 x 1023
References• Arnold B. Arons; Development of Concepts of
Physics• Aaron J. Ihde; The Development of Modern
Chemistry• Classic Chemistry;
http://web.lemoyne.edu/~giunta/• Classic Papers from the History of Chemistry;
http://www.chemteam.info/Chem-History/Classic-Papers-Menu.html
Thank you Dennis
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