Chemistry at karlsruhe 1860 using reacting to the past in general chemistry
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Chemistry at Karlsruhe 1860: Using Reacting to the Past in General Chemistry. David E. Henderson Trinity College Susan K Henderson Quinnipiac University. Philosophies of Science. Plato –describe nature by thinking about the ideal state rather then the real state (logic)

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Chemistry at Karlsruhe 1860: Using Reacting to the Past in General Chemistry

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Chemistry at karlsruhe 1860 using reacting to the past in general chemistry

Chemistry at Karlsruhe 1860: Using Reacting to the Past in General Chemistry

David E. Henderson

Trinity College

Susan K Henderson

Quinnipiac University


Philosophies of science

Philosophies of Science

  • Plato –describe nature by thinking about the ideal state rather then the real state (logic)

  • Aristotle –observe nature and then try to describe its properties and behavior

  • Empiricists –develop laws and relationships to describe nature only bydirect observations/measurements.

    • Not concerned with underlying causes.

  • Realists – Understanding underlying causes is necessary to fully explain observations

    • atoms must be considered to be real to fully describe how different arrangements of the same atoms can produce different properties.


Learning goals karlsruhe game

Learning Goals – Karlsruhe Game

  • History of the study of matter and its behavior referred to as “chemistry”

  • Evidence as the basis of chemical knowledge

  • The process of science

  • Development of quantitative skills


Karlsruhe conference

Karlsruhe Conference

  • First International Scientific Meeting

    • held inKarlsruhe, Germany, October 1860

  • Topics to be considered

    • Are Atoms Real?

    • What is the proper formula for water? HO, H2O

    • Can we assign atomic weights to elements or only equivalent weights?

      • Is Carbon 6 or 12? Oxygen 8 or 16?


Dalton s atomic theory 1808

Dalton’s Atomic Theory (1808)

  • Each element is made up of tiny particles called atoms.


Dalton s atomic theory continued

Dalton’s Atomic Theory (continued)

  • The atoms of a given element are identical; the atoms of different elements are different in some fundamental way or ways.


Dalton s atomic theory continued1

Dalton’s Atomic Theory (continued)

  • Chemical compounds are formed when atoms of different elements combine with each other. A given compound always has the same relative numbers and types of atoms.


Dalton s atomic theory continued2

Dalton’s Atomic Theory (continued)

  • Chemical reactions involve reorganization of the atoms—changes in the way they are bound together.

  • The atoms themselves are not changed in a chemical reaction.


Laws from dalton s theory

Laws from Dalton’s Theory

Law of conservation of mass

  • Mass is neither created nor destroyed

    Law of definite proportion

  • A given compound always contains exactly the same proportion of elements by mass.

    Law of multiple proportions

  • If two elements can combine to form more than one compound, the masses of one element that combines with a fixed mass of the other element are in ratios of small whole numbers

    CuO and Cu2O Fe 2O3 and FeO


Karlsruhe conference1

Karlsruhe Conference

  • Factions

    • Berzelian Empiricists (Bunsen, Frankland)

    • Liebig Empiricists (Liebig, Meyer)

    • Organic Realists (Williamson, Kekule)

    • Cannazzaro

    • Indeterminates (Pasteur, Mendeleev)


Berzelians

Berzelians

  • Prof Berzelius was one of the leading chemists at that time.

  • Berzelius performed over 2000 different experiments

    This group assigned relative weights of 1 for H, 6 for C and 16 for O. Meaning that C is 6 times as heavy as H, O is 16 times as heavy as H


Berzelians1

Berzelians

  • They reject anything that is not based on observation and measurement, ie empirical data

  • They believe that matter is composed of electropositive and electronegative atoms


Example of empirical data

Example of empirical data

  • Data for the Law of multiple proportions

    • 1 g oxygen reacts with 0.4375 g nitrogen

    • 1 g oxygen reacts with 0.8750 g nitrogen

    • 1 g oxygen reacts with 1.750 g nitrogen

    • Suggests that oxygen reacts with nitrogen to give three different compounds. Look at the ratios of the mass of nitrogen that reacts with 1 gram of oxygen

      • 0.8750/0.4375= 2

      • 1.750/0.4375= 4

      • NO, NO2, NO4 or NO1/2, NO, NO2 can’t tell which from this data


Liebig

Liebig

  • Prof. Justus Liebig and his group developed methods to analyze organic chemical

  • Like the Berzelians they dealt only with empirical data and equivalent weights

  • Organic Compounds generally are made up of carbon, hydrogen and oxygen

  • Organic compounds when combusted in air form water, and carbon dioxide

  • Liebig determined the simplest formulas (empirical formulas) of any compound of C, H and O which includes sugars, alcohols, and many others.

  • Liebig’s apparatus is still honored in the Am ChemSoc Logo


Gay lussac and avogadro 1809 1811

Gay-Lussac and Avogadro (1809—1811)

  • Gay—Lussac

    • Measured (under same conditions of T and P) the volumes of gases that reacted with each other. For Example for water H2O

    • But 1 g H combines with 8 g O  9 g water suggesting HO

    • Basic conflict between volume and mass measurements!


Gay lussac and avogadro 1809 18111

Gay-Lussac and Avogadro (1809—1811)

  • Avogadro’s Hypothesis

    • At the same T and P, equal volumes of different gases contain the same number of particles.

    • EVEN Hypothesis – Widely Accepted


The even hypothesis

The EVEN Hypothesis

  • Equal Volumes have even numbers

    • All gases are observed to follow this rule

  • Implication is that all atoms must be the same size since a filled container of different gases weigh different amounts

  • Therefore - Some atoms are heavier than others


Rise of organic chemistry

Rise of Organic Chemistry

  • Discovery of isomers

    • Same molecule but assembled differently

      • Butyl Alcohol and ether both same formula but different properties

      • Butyric acid and hydroxyethylene both C2H2O according to Liebig

        • One an acidic liquid and one a volatile alcohol

    • Idea of chemical structure related to properties

  • If arrangement of atoms is important, they must be real


Organic realists

Organic Realists

  • Many different organic compounds can have the same empirical formula but are very different, sugars are denoted as CH2O but glucose (blood sugar) and sucrose (table sugar) are two different substances.

  • The EVEN hypothesis is used to determine relative weights of organic compounds


Canizzaro

Canizzaro

  • StanisllaoCanizzaro, Prof of Chemistry in Genoa, Italy

  • Not well known


Indeterminates

Indeterminates

  • Every RTTP Game has indeterminates

  • They are assigned roles and may have secrets but they have no predetermined opinions about the issues being debated

  • In this game they will act as moderators of the game sessions.

  • Their votes are critical to the outcome, so they are the ones to be convinced


Things all factions believe are true

Things All Factions Believe are True

  • EVEN – Equal Volumes contain Equal Numbers

    • Hypothesis allows determination of relative weights of different compounds

  • Law of Multiple Proportions

    • Compounds contain fixed ratios of elements

    • Some elements combine in multiple ratios


Things all factions don t know

Things All Factions Don’t Know

  • The Mole Concept

  • Atomic Weights (Relative and Equivalent only)

  • The Periodic Table

  • Diatomic Nature of Elemental Gases, O2, H2

  • Whether Atoms are Real or just a useful idea

  • Relative weights of Carbon and Oxygen

  • Formulas of water and carbon oxides

  • Concept of Covalent Bonding


Data for the debate

Data for the Debate

  • Experimental data to be presented

    • Combination of Metals with oxygen (oxidation)

    • Combination of Metals with hydrogen (reduction)

    • Electrolysis (decomposition)

    • Combustion (burn organic molecule to decompose into Carbon, Hydrogen and Oxygen

    • Gas Density measurements allowed the relative weights of atoms and molecules to be determined


Game session 1

Game Session 1

  • Factions describe experiments

  • Factions present calculated results and conclusions from the data

  • Each faction makes different assumptions

    • Assumptions are based on empirical evidence

  • Answer keys for are provided for this workshop


Game session 2

Game Session 2

  • Examine the other groups data using your assumptions

  • Look for consistent results

  • Make arguments for your faction’s objectives


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