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Organic Chemistry Review Questions for AP Chemistry

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By — McGraw-Hill Professional
Updated on Feb 2, 2011

Review the following concepts if necessary:

Problems

You have 5 minutes. You may not use a calculator. You may use the periodic table at the back of the book. For each question, circle the letter of your choice.

  1. Cycloalkanes are hydrocarbons with the general formula CnH2 n. If a 0.500 g sample of any alkene is combusted in excess oxygen, how many moles of water will form?
    1. 0.50
    2. 0.072
    3. 0.036
    4. 1.0
    5. 0.018
  2. The organic compound shown above would be classified as

    1. an organic base
    2. an ether
    3. an alcohol
    4. an aldehyde
    5. a ketone
  3. Which of the following compounds is optically active?
    1. CH3CHClCH2CH2CH3
    2. CH3CH=HCH2CH3
    3. CH3CH2CHClCH2CH3
    4. CH3CH2CH2CH2OH
    5. CH3CH2CH2CH2CH3
  4. A carboxylic acid may be represented as:
    1. ROH
    2. RCHO
    3. R-O-R'
    4. RCOOH
    5. RCOOR'

Answers and Explanations

  1. C—The general formula, CnH2n, means that 1 mol of H2O will form per mole of empirical formula unit, regardless of the value of n. The moles of water formed is the mass of the alkene divided by the empirical formula mass.
  2. (0.500 g alkene)(l mol alkene/14 g alkene)(l mol H2O/mol alkene)

    = 0.036 mol

  3. C—Organic bases are, in general, amines (contain N). An ether would have an oxygen single-bonded to two carbons (R groups). An aldehyde has oxygen double-bonded to a carbon at the end of a chain. Aldehydes (RCHO) and alcohols (ROH) are often confused, because of the similarity in their general formulas. Ketones have oxygen double-bonded to a carbon not at the end of a chain.
  4. A—Redrawing the structures may help you to recognize the correct answer. An optical isomer must be a carbon atom with four differentgroups attached to it. For A the groups on the second carbon are: CH3–,H, Cl, and –CH2CH2CH3. Answer C is misleading. It is similar to A, but two of the groups, the –CH2CH3 groups, are the same.
  5. D—A = alcohol B = aldehyde C = ether E = ester
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