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Experiment 1:

Experiment 1:. STRUCTURE, INTERMOLECULAR FORCES AND SOLUBILITY. ROLE OF INTER- AND INTRAMOLECULAR FORCES. physical state; solid, liquid & gas solid vs. liquid: (fat vs. oil) liquid vs. gas: (C 2 H 6 O isomers: dimethyl ether vs. ethanol) distillation; difference in BP ( o C)

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Experiment 1:

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  1. Experiment 1: STRUCTURE, INTERMOLECULAR FORCES AND SOLUBILITY

  2. ROLE OF INTER- AND INTRAMOLECULAR FORCES • physical state; solid, liquid & gas • solid vs. liquid: (fat vs. oil) • liquid vs. gas: (C2H6O isomers: dimethyl ether vs. ethanol) • distillation; difference in BP (oC) • extraction; difference in solubility and partition coefficient. • Oil and vinegar dressing • Chromatography: different IMF between analyte and stationary vs. mobile phase • GC of alkanes, TLC, HPLC of analgesics • Biology • secondary structure of proteins: H-bonding between amino acids • DNA and DNA-RNA base pairing: H-bonding between base pairs

  3. INTERMOLECULAR FORCES • London Dispersion Forces: weak attractive forces caused by instantaneous dipoles in molecules. • Dipole-Dipole Forces: Electrostatic attraction between polar molecules. • Ion-Dipole Forces: Electrostatic attraction between an ion and a polar solvent. • Hydrogen Bonding: (2-3 kcals/mole) Electrostatic attraction between the very electropositive H of -O-H and -N-H bonds withthe negative end of other dipoles, especially with oxygen and nitrogen atoms.

  4. DIPOLE - DIPOLE FORCES: • Dipole momentm: Electrostatic attraction between polar molecules. • measure of the unevenness of electron density in a bond or molecule. • depends on both electronegativityof atoms and on molecular geometry.

  5. HYDROGEN BONDING

  6. GOALS OF LAB • Introduction to drawing structures. • Introduction to inter- and intra-molecular forces between organic molecules. • Through solubility testing, discover relationship between structure, intermolecular forces and solubility.

  7. EXPERIMENTAL OUTLINE • A: Test solubility of compounds in hexane and water. • B: Test solubility of organic liquids in water. • C: Test solubility of alcohols in hexane and water. • D: Test solubility of organic solids in diethyl ether, water, acidic and basic solutions.

  8. Table of Common Organic Solvents

  9. SAFETY CONCERNS • All solvents used in today’s lab are volatile. Wear safety goggles at all times, and use fume hoods.

  10. WASTE DISPOSAL • All waste from this experiment goes into the bottle marked: “Solubility Waste (IMF)”.

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