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2.E: Polar Covalent Bonds; Acids and Bases (Exercises)

  • Page ID
    61689
  • These are the homework exercises to accompany the Textmap for McMurry's Organic Chemistry textbook.

    2.1 Polar Covalent Bonds: Electronegativity

    2.1 Exercises

    Questions

    Q2.1.1

    Rank the following from least polar to most polar using knowledge of electronegativity

    CH3CH2-Li CH3CH2-K CH3CH2-F CH3CH2-OH

    Solutions

    S2.1.1

    (least polar) OH < F < Li < K (most polar)

     

    2.2 Polar Covalent Bonds: Dipole Moments

    2.2 Exercises

    Questions

    Q2.2.1

    The following molecule has no dipole moment in the molecule itself, explain.

    Q2.2.2

    Which of the following molecules has a net dipole?

    Q2.2.3

    Within reactions with carbonyls, such as a reduction reaction, the carbonyl is attacked from the carbon side and not the oxygen side. Using knowledge of electronegativity explain why this happens.

    Solutions

    S2.2.1

    The hydroxyl groups are oriented opposite of one another and therefore the dipole moments would “cancel” one another out. Therefore having a zero net-dipole.

    S2.2.2

    1, 3, and 4 have a net dipoles.

    S2.2.3

    The oxygen is more electronegative than the carbon and therefore creates a dipole along the bond. This leads to having a partial positive charge on the carbon and the reduction can take place.

    2.3: Formal Charges

    2.3 Exercises

    Questions

    Q2.3.1

    Give the formal charges for all non-hydrogen atoms in the following moelcules:

    BH4, H2O, CH3O

    Solutions

    S2.3.1

    BH4 (B = −1)

    H2O (O = 0)

    CH3O (C = 0, O = −1)

    2.4 Resonance

    2.4 Exercises

    Questions

    Q2.4.1

    Draw the resonance structures for the following molecule:

    Solutions

    S2.4.1

    2.5 Rules for Resonance Forms

    2.5 Exercises

    Questions

    Q2.5.1

    Are all the bond lengths the same in the carbonate ion, CO32-?

    Solutions

    S2.5.1  Yes, the bond lengths in carbonate ion are all the same.  Carbonate ion exists as the resonance hybrid of the three resonance forms below.

    2.7 Acids and Bases: The Brønsted-Lowry Definition

    2.7 Exercises

    Questions

    Q2.7.1

    Is the following molecule a Brønsted acid or base?

    HSO4

    Solutions

    S2.7.1

    It can be both, consider the following schemes:

    2.9 Predicting Acid-Base Reactions from pKaKa Values

    2.9 Exercises

    Questions

    Q2.9.1

    In the following reactions give the resulting products and label the conjugate acid and bases.

    Solutions

    S2.9.1

    2.10 Organic Acids and Organic Bases

    2.10 Exercises

    Questions

    Q2.10.1

    Determine which of the one of the molecules is an acid or a base.

    Solutions

    S2.10.1

    1 = Base

    2 = Acid

    3 = Acid

    4 = Acid

    2.11 Acids and Bases: The Lewis Definition

    2.11 Exercises

    Questions

    Q2.11.1

    For the following molecules state wither they are Lewis acid or base and wither or not they are a Brønsted acid or base.

    Solutions

    S2.11.1

    Acetone is a Lewis base and a Brønsted base. Ammonium cation is both a Lewis acid and a weak Brønsted acid.