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Chemistry LibreTexts

11.1: Exercises

  • Page ID
    213758
  • Assign one of the structures A – J presented on page 2 to each of the IR spectra provided (1 – 10). Base your assignment on one or more key frequencies, according to guidelines presented in the recitation notes and on p. A19–A31 of your textbook. Especially useful are p. A19 and A20. For each spectrum do the following:

    1. Mark key absorption frequencies in the spectrum, and associate each with a specific bond (e.g. O–H, C=O). Keep in mind that there are usually only one or two key bands in each spectrum, although in some cases you might observe up to three. Do not label the alkane C–H stretch, since these bands are present in most organic compounds.

    2. Assign a letter from the structures given (A – J). There is only one structure per spectrum.

    3. Identify the main functional group present in the structure (i.e. ketone, alcohol, etc.).

    4. Provide approximate frequency values for the bands you labeled in the spectrum (in cm–1), and identify their shape (broad, medium, or narrow) and intensity (weak, medium, or strong). Each of the above items is worth 2.5 points, for a total of 10 points per question.

    Each of the above items is worth 2.5 points, for a total of 10 points per question.

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    Key Bands

    Bond: O-H Approximate frequency: 3000 Shape: broad Intensity: strong
    Bond: C=O Approximate frequency: 1700 Shape: medium Intensity: strong

    INCOMPLETE OR UNCLEAR ANSWERS WILL RECEIVE NO CREDIT

    STRUCTURES

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    KEY BANDS

    Bond: _______ Approximate frequency: _______ Shape: ________ Intensity: ________
    Bond: _______ Approximate frequency: _______ Shape: ________ Intensity: ________
    Bond: _______ Approximate frequency: _______ Shape: ________ Intensity: ________

    GRADE: ___________

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    KEY BANDS: 

    Bond: __________ Approximate frequency: _________ Shape: _____________ Intensity: ___________
    Bond: __________ Approximate frequency: _________ Shape: _____________ Intensity: ___________
    Bond: __________ Approximate frequency: _________ Shape: _____________ Intensity: ___________

    GRADE: ___________

    clipboard_e068bee6ac905e447aaff9366963315fb.png

    clipboard_eec0278cf1f947319bc8d0a8b9d87649d.png

    KEY BANDS: 

    Bond: _________ Approximate frequency: ________ Shape: _________ Intensity: _________
    Bond: _________ Approximate frequency: ________ Shape: _________ Intensity: _________
    Bond: _________ Approximate frequency: ________ Shape: _________ Intensity: _________

    GRADE: _______

     

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    KEY BANDS: 

    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________

    GRADE: _________

     

    clipboard_e83e460712228e462ee211b2f0190bf64.png

    KEY BANDS: 

    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________

    GRADE: _________

    clipboard_e95cf03f01f7c96656b3e01d91933e04e.png

    KEY BANDS: 

    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________

    GRADE: _________

     

    clipboard_e4464db52091f4291cb458613ef59898e.png

    KEY BANDS: 

    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________

    GRADE: _________

     

    clipboard_edf3384c086dc91e0cbfe7f32acdb3ee0.png

    KEY BANDS: 

    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________

    GRADE: _________

    clipboard_ef4ea9c47971663e0be4ff738fe9a520c.png

    clipboard_edf3384c086dc91e0cbfe7f32acdb3ee0.png

    KEY BANDS: 

    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________

    GRADE: _________

     

    clipboard_e29dea38731baee2a4829a5cf0b80d7ce.png

    KEY BANDS: 

    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________
    Bond: _________ Approximate frequency: _______ Shape: __________ Intensity: ________

    GRADE: _________

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