Skip to main content
Chemistry LibreTexts

4.P: Problems for Chapter 4

[ "article:topic", "Lower Division", "Organic", "Author tag:Soderberg", "authorname:soderberg", "authorname:soderbergt", "showtoc:no" ]
  • Page ID
    1054
    • Contributed by

    link to Solution Manual

     

    P4.1: Which represents a higher energy frequency of electromagnetic radiation, 1690 cm-1 or 3400 cm-1? Express each of these in terms of wavelength (meters) and frequency (Hz).

    P4.2: Calculate the value, in kcal/mol, of the energy gap associated with a typical ketone carbonyl stretching transition at 1720 cm-1.

    P4.3: Explain how you could use IR spectroscopy to distinguish between compounds I, II, and III.

    image076.png

    P4.4: Explain how you could use IR spectroscopy to distinguish between compounds A, B, and C.

    image078.png

    P4.5: Explain how you could use IR spectroscopy to distinguish between compounds X, Y, and Z.

    image080.png

    P4.6: A 0.725 mL aqueous solution of NADH shows an absorbance at 340 nm of 0.257.  Express (in nanamole (nm) units) how much NADH is contained in the sample.

    P4.7: A 1 mL enzymatic reaction mixture contains NADH as one of the reactants, and has a starting A340 = 0.345.  After the reaction is allowed to run for five minutes, the researcher records a value of A340 = 0.125.  How many nm of NADH are used up per minute, on average, in this reaction?

    P4.8: The reaction below is of a type that we will study in Chapter 11.  While the two starting materials are only slightly colored, the product is an intense orange-red.  Account for this observation.

    image082.png

    P4.9: Predict five fragments that you would expect to be evident in the mass spectrum of 3-methyl-2-pentanone.

    P4.10: One would expect the mass spectrum of cyclohexanone to show a molecular ion peak at m/z = 98. However, the m/z = 98 peak in the cyclohexanone spectrum is unusually tall, compared to the molecular ion peaks in the mass spectra of other ketones such as 2-hexanone or 3-hexanone. Explain.

    P4.11: Which would be more useful in distinguishing the two compounds shown below: IR or UV spectroscopy?  Explain.

    image084.png

    P4.12: Which analytical technique – IR, UV, or MS - could best be used to distinguish between the two compounds below?  Explain.

    image086.png

     

    Contributors