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2.1: Chemistry Tutorial

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    48546
  • 2.1 Chemistry Tutorial

    The chemical compounds that are important for understanding most of the chemistry in this course are organic - that means that the compounds primarily contain carbon, hydrogen, and oxygen atoms (also sulfur and nitrogen). They can also be called hydrocarbons. The basic structures that we will be discussing in this course are called: 1) alkane (aka aliphatic), 2) branched alkane, 3) cycloalkane, 4) alkenes (double-bonds), 5) aromatic, 6) hydroaromatic, and 7) alcohols. First, I will show the atoms and how they are connected using the element abbreviation and lines as bonds, and then I will show abbreviated structural representations.

    1. Alkane - atoms are lined up. For stick representation, each corner represents a CH2 group, and each end represents a CH3 group.

    Name Atoms and Bonds Stick Representation
    Heptane (7 C atoms) Straight Line of 7 C's connected to each other. The two end C's have 3 H's connected to it and all the others have 2 H's Zigzag line with 7 corners (including the ends). Each corner (including the ends) represent one carbon

    2. Branched Alkane - still an alkane, but instead of a straight line, the carbons are branched off of each other.

    Name Atoms and Bonds Stick Representation
    Isobutane (4 C atoms) Straight line of 3 Cs. The two end C's have 3 H's attached and the middle C has one H and one branch with a CH3 group Three lines making a Y shape. Each end of the Y and the intersection represent a carbon
    Isopentane (5 C atoms) Straight line of 4 Cs. The 2 end C's have 3H's attached & one of the middle Cs has 1 H and 1 branch with a CH3 group, the other C has 2 H's Zigzag with four corners (including the ends) and one branch of off 1 of the internal corners

    3. Cycloalkanes - again, still an alkane, but forms a ring compound.

    Name Atoms and Bonds Stick Representation
    Cyclohexane (6 C atoms) hexagon with a CH2 at every vertice hexagon

    4. Alkenes - alkanes that contain a double bond.

    Name Atoms and Bonds Stick Representation
    Pentene (5 C atoms) line of 4 Cs connected by single lines (bond) and a fifth C connected with a = (double bond) zig zag with 5 vertices including the ends. The last segment of the zigzag is a = (double bond)

    5. Aromatic - hydrocarbon ring compound with single and double bonds, significant differences in properties.

    Name Atoms and Bonds Stick Representation
    Benzene (6 C atoms) hexagon with CH on every vertice. Every other edge has a double bond (two lines) hexagon with every other side having two lines, hexagon with a circle inside representing the same as alternating double lines

    6. Hydroaromatics - hydrocarbon ring compound with an aromatic and an alkane in one molecule.

    Name Atoms and Bonds Stick Representation
    1,2,3,4-tetrahydronaphthalene, aka tetralin (10 C atoms) hexagon with alternating double bonded sides connected along a single bonded side to a hexagon with single bonds hexagon with a circle inside connected along one side to a hexagon

    7. Alcohols - hydrocarbon with -OH functional group.

    Name Atoms and Bonds Stick Representation
    Butanol (4 C atoms) Line of 4 Cs in a row. The first C has 3Hs the last 3 have 2Hs connected and the final C also has an -OH connected Zig zag with 5 vertices including the ends. One of the end vertices has an OH attached to it
    Ethanol (2 C atoms) A CH3 connected to a CH2 connected to an -OH zig zag with 3 corners including the ends with an OH connected to one end corner

    The following table shows common hydrocarbons and their properties. It is important to know the properties of various hydrocarbons so that we can separate them and make chemical changes to them. This is a very brief overview - we will not yet be going into significant depth as to why the differences in chemicals affect the properties.

    Table 2.1: List of Common Hydrocarbons and Properties

    Name Number of C Atoms Molecular Formula

    bp

    (°C), 1 atm

    mp

    (°C)

    Density

    (g/mL) (@20°C)
    Methane 1 CH4 -161.5 -182 --
    Ethane 2 C2H6 -88.6 -183 --
    Propane 3 C3H8 -42.1 -188 --
    Butane 4 C4H10 -0.5 -138 --
    Pentane 5 C5H12 36.1 -130 0.626
    Hexane 6 C6H14 68.7 -95 0.659
    Heptane 7 C7H16 98.4 -91 0.684
    Octane 8 C8H18 125.7 -57 0.703
    Nonane 9 C9H20 150.8 -54 0.718
    Decane 10 C10H22 174.1 -30 0.730
    Tetradecane 14 C14H30 253.5 6 0.763
    Hexadecane 16 C16H34 287 18 0.770
    Heptadecane 17 C17H36 303 22 0.778
    Eicosane 20 C20H42 343 36.8 0.789
    Cyclohexane 6 C6H12 81 6.5 0.779
    Cyclopentane 5 C5H10 49 -94 0.751
    Ethanol 2 C2H6O 78 -114 0.789
    Butanol 4 C4H10O 118 -90 0.810
    Pentene 5 C5H10 30 -165 0.640
    Hexene 6 C6H12 63 -140 0.673
    Benzene 6 C6H6 80.1 5.5 0.877
    Naphthalene 10 C10H8 218 80 1.140
    1,2,3,4-Tetrahydronaphthalene 10 C10H12 207 -35.8 0.970
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