Properties of Organic and Properties of Organic and Inorganic CompoundsInorganic Compounds
Experiment 1Chem 121 Organic Chemistry Laboratory
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What is ORGANIC CHEMISTRY?
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IntroductionIntroductionVital force – ‘vitalism’Friedrich Wohler overthrew vitalism
◦Synthesis of urea from ammonium cyanate
Distinguishing feature: organic compounds all contain the CARBON atom
NH4+
C-
N
O
NH2 NH2
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What is ORGANIC What is ORGANIC chemistry?chemistry?the study of carbon containing
compounds◦Other elements in organic
compounds: H, O, N, S, P, Cl, Br, I and other transition metals
Why Carbon?◦Can share four valence electrons◦Form strong covalent bonds◦Form rings and long chains, e.g.
benzene and DNA4
Definition of termsDefinition of termsIonic compounds: compounds made
up of a metal cation and a nonmetal anion◦e.g. NaCl, KNO3
Intramolecular forces of attraction: forces existing within molecules that holds the atoms together◦e.g. Ionic bond, covalent bond, metallic
bondIntermolecular forces of attraction:
forces existing between molecules5
Intermolecular Forces of Intermolecular Forces of AttractionAttractionIon-dipole
◦Between an ionic compound and a polar compound e.g. NaCl dissolved in water
Dipole-dipole◦Between two polar compounds
e.g. HCl dissolved in water
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Hydrogen Bonding◦Requirement: H atoms bonded to F,
O, N◦Strongest intermolecular force◦e.g. NH3 in H2O
London dispersion forces/van der Waals forces◦Between two NONPOLAR
compounds◦Weakest intermolecular force;
present in all organic molecules
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The larger the size of the organic compound, the
larger the London dispersion forces.
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Properties of Organic Properties of Organic CompoundsCompoundsFlammable
◦Due to the C-C bond energies in organic compounds
◦Energy released is in the form of heat
Ethanol vs. Water◦Ethanol – produces the distinct blue
flame◦Water – smothers flame instead of
generating one
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Charring ◦also known as burning, scorching◦organic compounds are sensitive to
heat◦End result of charring: elemental C
Sucrose• disaccharide• common ingredient in sweet foods like ice cream, candy• also works as a food preservative
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IMF of sucrose: London dispersion force
IMF of NaCl and CaCO3: no intermolecular force, but intramolecular (IONIC BOND)
Remember always: Intramolecular forces are way STRONGER than intermolecular forces.
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Solubility◦relies on the intermolecular forces of
organic compounds◦‘like dissolves like’◦Polar solvents dissolve in polar solutes.◦Nonpolar solvents dissolve in nonpolar
solutes.◦Organic compounds = mostly nonpolar
It only follows that most organic compounds are soluble in organic solvents.
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Naphthalene in ether
◦ No ionic bonds, just pure London dispersion forces
Naphthalene in water
Water is capable of hydrogen bonding; naphthalene cannot
CH3
O
CH3
H
O
H
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Electrical ConductivityElectrical Conductivity
Electrical conductivity is only possible when a compound contains charged particles (i.e. an electrolyte)◦e.g. NaCl, NaNO3 are electrolytes
Since most organic compounds are molecular, not ionic, it does not conduct electricity.
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1 M sucrose
1 M ethanol
CH3 O
H
1 M NaCl
hexane
Na+
Cl-
CH3 CH3
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SummarySummaryOrganic chemistry is the study of
carbon compounds.Organic compounds have the ff
properties:◦Flammable◦Combustible◦Immiscble in polar solvents like
water◦Non-electrolytes; do not conduct
electricity16
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