Chemistry 1020 Laboratory

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Chemistry 1020 Laboratory
Classification of Organic Compounds
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Hydrocarbon

• Hydrocarbons are the fundamental framework of
  organic compounds, which contain only hydrogen
  and carbon

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Hydrocarbon Classes

• Hydrocarbons can be classified into three classes
  based on their structure and chemical behavior
  alkane, alkene and alkyne, aromatic hydrocarbon
• Various classes of hydrocarbons react differently
  with many reagents

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Alkane

• Saturated, single bond (C-C)
• CnH2n2 CH4, C2H6, C3H8
• H3C - CH3, H3C - CH2 - CH3

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Alkene and Alkyne

• Alkene Unsaturated, double (CC)
• CnH2n C2H4, C3H6, C4H8
• H2C CH2, H2C CH - CH3,
• H2C CH CH2 - CH3
• Alkyne Unsaturated, triple bond (C?C)
• CnH2n-2 C2H2, C3H4, C4H6
• HC ? CH, HC? C - CH3, HC?C CH2 - CH3

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Aromatic Hydrocarbon

• Benzene cyclic structure, hybridized bond that
  are intermediate in behavior to single and double
  bonds
• C6H5-CH3, C6H5-CH2-CH3

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Combustion

• The type and color of flame and smoke are
  different due to their different amount of carbon
  content
• The extent of oxidation for the same hydrocarbon
  could be different
• 2C2H6 3O2 4C 6H2O
• 2C2H6 5O2 4CO 6H2O
• 2C2H6 7O2 4CO2 6H2O

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Saturation

• Bromine (Br2)
• - react very slowly with alkanes
• - easily adds to multiple bonds of alkenes and
  alkynes
• - react with aromatic hydrocarbon only in the
  presence of a catalyst (iron)
• red-brown disappear
• - remain red-brown

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Oxidation

• Potassium permanganate (KMnO4) a strong
  oxidizing agent
• - react very slowly and lesser extent with
  alkanes
• - attack the more reactive double bonds of
  alkenes and alkynes, forming compounds of higher
  oxidation state
• - dont react with aromatic hydrocarbon because
  of unusual stability of the aromatic ring
  structure
• pink disappears
• - remain pink

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Safety

• Organic solvent used are very volatile and
  flammable, and their vapors are explosive in air
  so be extremely careful with open flames
• The unknowns should be treated as if they are
  toxic and flammable, should be handled very
  carefully
• Wastes should be collected and never thrown in
  the sink

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Pre-lab Questions

• You have to know the names and structures of a
  compound in different classes of hydrocarbons
• You have to know the equation balance for
  different products in the combustion
• You have to know the different classes of
  hydrocarbons have different reactivity
• Know how to classify an unknown from the test
  results