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    Alkanes: Alkane Homologous Series. The Alkanes Form A Homologous Series. A Hydrocarbon

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    Vannah Romasanta
    Alkanes are a homologous series of saturated hydrocarbons with the general formula CnH2n+2. They contain only single bonds and exhibit weak intermolecular forces. Common physical properties include low melting and boiling points. Alkanes undergo combustion, burning in oxygen to produce carbon dioxide and water. They are primarily obtained from petroleum and natural gas.

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    Alkanes: Alkane Homologous Series. The Alkanes Form A Homologous Series. A Hydrocarbon

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    Vannah Romasanta
    25 views9 pages
    Alkanes are a homologous series of saturated hydrocarbons with the general formula CnH2n+2. They contain only single bonds and exhibit weak intermolecular forces. Common physical properties include low melting and boiling points. Alkanes undergo combustion, burning in oxygen to produce carbon dioxide and water. They are primarily obtained from petroleum and natural gas.

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    Alkanes are a homologous series of saturated hydrocarbons with the general formula CnH2n+2. They contain only single bonds and exhibit weak intermolecular forces. Common physical properties include low melting and boiling points. Alkanes undergo combustion, burning in oxygen to produce carbon dioxide and water. They are primarily obtained from petroleum and natural gas.

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    © All Rights Reserved
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    Download as docx, pdf, or txt
    25 views9 pages

    Alkanes: Alkane Homologous Series. The Alkanes Form A Homologous Series. A Hydrocarbon

    Uploaded by

    Vannah Romasanta
    Alkanes are a homologous series of saturated hydrocarbons with the general formula CnH2n+2. They contain only single bonds and exhibit weak intermolecular forces. Common physical properties include low melting and boiling points. Alkanes undergo combustion, burning in oxygen to produce carbon dioxide and water. They are primarily obtained from petroleum and natural gas.

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    of 9

    ALKANES

    Name of series:

     Alkane Homologous Series. The alkanes form a homologous series. A hydrocarbon


    homologous seriesis a series of hydrocarbons which: Have the same general formula.

    General Formula: C nH2n+2 or C-C or C-H

    Hybridization: sp3; the carbon atoms will join to each other by forming sigma bonds by the end-to-end
    overlap of their sp3 hybrid orbitals.
    Name of the first member:

    Common: Natural Gas / Marsh Gas

    IUPAC: Methane - CH4

    Physical Properties:

     Alkane contain only NONPOLAR C-C and C-H bond.


     They exhibit only WEAK INTERMOLECULAR FORCES.
     LOW MELTING POINT
     LOW BOILING POINT
     LOW MOLECULAR WEIGHT are gases at room temperature
     Melting point and boiling point of alkanes increases as the number of carbon increases.
     Increased surface area increases the force of attraction between molecules, thus RAISING the
    boiling and melting point.
     Nonpolar alkanes are WATER INSOLUBLE and less dense than water.

    Reaction with combustion:

     It has NO FUNCTIONAL GROUP


     ALKANES undergo combustion, they BURN in the presence of oxygen to form carbon dioxide
    (CO2) and water.
     Every C-H and C-C bond in the starting material is converted to a C-O bond in the product.
    Examples:
    CH4 + 2 O2 flame CO2 + 2 H2O + Energy
    Methane
    (Natural Gas)
     Combustion of alkanes in a form of natural gas, gasoline, or heating oil RELEASES ENERGY for
    heating homes, powering vehicles, and cooking food.
     A spark or flame is needed to initiate combustion.
     The combustion of Alkanes and other hydrocarbons obtained from fossil fuels adds a
    tremendous amount of CO2 to the atmosphere.
     When there is not enough oxygen available to completely burn a hydrocarbon, INCOMPLETE
    COMBUSTION may occur and CARBON MONOXIDE (CO) is formed instead of carbon dioxide
    (CO2)

    Incomplete 2 CH4 + 3 O2 Flame 2 CO + 4 H2O + Energy


    Combustion carbon monoxide

    Sources/Uses:

     Principle source is PETROLEUM and NATURAL GAS.


     Two common processes to convert alkanes into other alkanes.
     Isomeration- straight chains into branched chains.
     Cracking – long chains into smaller chains.

    General and other interesting information:

     ALKANES are hydrocarbons having only C-C and C-H single bonds.
     Alkanes that contain chains of carbon atoms but no rings are called ACYCLIC ALKANES. Have a
    molecular formula CnH2n+2.
     CYCLOALKANE contains carbons joined in one or more rings. Its general formula is CnH2n.
     Undecane and cyclohexane are examples of two naturally occurring alkanes.
     PHEROMONE, a chemical substance used for communication in a specific animal species, most
    commonly an insect population.
     ISOMERS –two different compounds with the same molecular formula.
     One of the two major classes of isomers is called CONSTITUTIONAL ISOMERS. it differs in the
    way the atoms are connected to each other.
     Example of constitutional alkanes having a formula of C5H12, Pentane, isopentane (2-
    methylbutane) and neopentane (2, 2-dimethylpropane).
     Primary Carbon bonded with one carbon
     Secondary Carbon bonded with two carbon
     Tertiary Carbon bonded with three carbon
     Quaternary Carbon bonded with four carbon
     A systematic naming of compounds (a system of nomenclature) was developed by the IUPAC
     Systematic- follows the accepted rules of nomenclature; IUPAC name.
     Generic- is the official, internationally approved name of drug.
     Trade- name for drug is assigned by the company that manufactures it.
     Alkyl group is formed by removing one hydrogen from the alkane.
     Cycloalkanes contain carbon atoms arranged in a ring.
     Natural gas is composed of largely of methane.
     Petroleum is a complex mixture of compounds, contains 1-40 carbon atoms.
     Refining is the separation into usable fractions that differ in boiling point.
     Oxidation results in an increase in the number of C-O bonds or decrease of C-H bonds.
     Reduction results in a decrease in the number of C-O bonds or an increase of C-H bonds.
    General Reaction:

    Name: SUBSTITUTION

    - It is a reaction in which an atom is replaced by another atom or group of atoms.

    - In a substitution reaction, one atom is swapped with another atom. These are very
    useful reactions in the chemical industry because they allow chemists to change one
    compound into something more useful, building up designer molecules like drugs.

    Reactants: Acyclic alkanes and Cycloalkanes

    Products: Alkyl Halide

    Catalyst: Temperature or Light

    Example:

    Methane + bromine → methylbromine + hydrogen bromide

    CH4 + Br2 → CH3Br + HBr

    This reaction is a substitution reaction because one of the hydrogen atoms from the
    methane is replaced by a bromine atom.

    Specific Reaction:

    Name: HALOGENATION OF ALKANES

     The reaction of a halogen with an alkane in the presence of ultraviolet (UV) light or
    heat leads to the formation of a haloalkane (alkyl halide).

    Reactants: Alkane & Halogens (Chlorine (Cl2) or Bromine (Br2))

    Products: Alkyl Halide (RCl or RBr) and Hydrogen Halide (HCl or HBr)

    Catalyst: Temperature or Light or Heat

    ALKANE + HALOGEN 250-400 C HALOALKANE + HYDROGEN HALIDE

    or light or heat

    Example: Methane + Cl - Cl Light Chloromethane + H - Cl


    ALKENES
    Name of series:

     The general formula for the homologous series of alkenes is CnH2n where n is the number of
    carbon atoms. Because alkenes are hydrocarbons with at least one carbon-carbon double bond the
    alkene homologous series starts at ethene C2H4.

    General Formula: CnH2n or C=C or C=H

    Hybridization: sp2; since each carbon of ethylene is surrounded by three atoms, each carbon is trigonal
    planar. They lie on the same plane and all bond angles are 120⁰.
    Name of the first member:

    Common: Ethylene

    IUPAC: Ethene - C2H4

    Physical Properties:

     NONPOLAR C-C and C-H bonds.


     LOW MELTING POINT
     LOW BOILING POINT
     INSOLUBLE IN WATER
     Alkenes are soluble in non-polar solvents.
     Alkenes with 2, 3 or 4 carbon atoms in the chain are gases at room temperature and pressure.

    Reaction with combustion:

     Complete combustion occurs when there is sufficient (or excess) oxygen. In a complete
    combustion reaction, alkanes react to form carbon dioxide and water
     If the combustion is not complete, products are CO, C (soot) and H2O.
     More soot (carbon) is produced compared to the corresponding alkane, due to a higher
    percentage by mass of carbon.
     Alkenes burn with a sooty and luminous flame because of the higher percentage of carbon in
    alkene particles. Unburnt Carbon particles present in the flames makes it sooty.

    Sources/Uses:

     Alkenes can be obtained from alkanes by the process of cracking.


     Alkenes can also be obtained by cracking of natural gas. This method is applied if the natural gas
    contains appreciable amounts of ethane, propane and butane.
     Alkenes are produced by hydrocarbon cracking.
     They are used as starting materials in the syntheses of alcohols, plastics, laquers, detergents,
    and fuels.
     The most important alkenes for the chemical industry are ethene, propene and 1,3-butadiene.
     Used as Feed stock for polymers like polyethene that can be easily found as one of the
    materials for clothes.

    General and other interesting information:

     Alkenes are compounds that contain a carbon-carbon double bond.


     Ethylene is a hormone that regulates plant growth and fruit ripening.
     Alkenes are also called as unsaturated hydrocarbons.
     Unsaturated hydrocarbons are compounds that contain fewer than the maximum number of
    hydrogen atoms per carbon.
     Cis isomer – when two CH3 groups are on the same side.
     Trans isomer – when CH3 groups are on the opposite side.
     Stereoisomers are isomers that differ only in the 3-D arrangement of atoms. Atoms are bonded
    to same atoms.
     Constitutional isomers differ in the way the atom is bonded to each other. Atoms are bonded
    to different atoms.
     Fatty acids are carboxylic acids (RCOOH) with long carbon chain of 12-20 carbon atoms.
     Saturated fatty acids have no double bonds in their long hydrocarbon chains.
     Unsaturated fatty acids have one or more double bonds in their long hydrocarbon chains.
     Lycopene, red pigment in tomatoes and watermelon. Act as an Antioxidant.
     Tamoxifen is a potent anticancer drug that contains a carbon-carbon double bond in addition to
    other functional groups. Treatment for breast cancer.
     Reaction of an alkene with hydrogen is called hydrogenation. Is an addition reaction in which
    two bonds are broken- one bond of the c-c double bond and the H-H bond- and two new C-H
    binds are formed.
     Metal catalyst provides a surface that binds both the alkene and H2, and speed up the reaction.
     Halogenation results in the addition of halogen (X2) to an alkene. It occurs with Cl2 and Br2.
     Hydrohalogenation results in the addition of HX (X= Cl or Br) to an alkene. It occurs with HCl
    and HBr.
     Markovnikov’s rule was named after a Russian chemist who first determined the selectively of
    the addition of HX to an alkene.
     Hydration results in the addition of water to an alkene. It occurs only if a strong acid such as
    H2SO4 is added to the reaction.
     Ethanol is used as a gasoline additive. Can be formed by fermentation of carbohydrates in
    grains and potatoes.
     Polymers are large molecules made up of repeating units of smaller molecules- called
    monomers- covalently bonded together.

    General Reaction:

    Name: ADDITION REACTION

     Addition is a reaction in which elements are added to a compound.


     New groups X and Y are added to a starting material.
    Reactants: Alkene & hydrogen (H2)/ halogens (Cl2 and Br2)/ hydrogen Halides (HCl and HBr)/

    Water (H2O)

    Products:

    Catalyst:

    Specific Reaction/s:

    A.

    Name: ADDITION OF HYDROGEN or Hydrogenation

     Halogenation results in the addition of halogen (X2) to an alkene.

    Reactants: Alkene & Hydrogen

    Products: Alkane

    Catalyst: Metal Catalyst (Palladium [Pd])

    B.

    Name: ADDITION OF HALOGEN or Halogenation

     Halogenation results in the addition of halogen (X2) to an alkene.

    Reactants: Alkene & Halogens (Cl or Br)

    Products: Dihalide

    Catalyst:
    C.

    Name: ADDITION OF HYDROGEN HALIDES or Hydrohalogenation

     Hydrohalogenation results in the addition of HX.

    Reactants: Alkene & Halogens (Cl or Br) & Hydrogen

    Products: Alkyl Halide

    Catalyst:

    D.

    Name: ADDITION OF WATER or Hydration

     Hydration results in the addition of water to an alkene.

    Reactants: Alkene & Water (H2O)

    Products: Alcohol

    Catalyst: Sulfuric acid or Phosphoric Acid

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