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Chem 234 Exam 1.
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Exam of 15 pages for the course Bnsf-Maintenance of Way Operating Rules at Bnsf-Maintenance of Way Operating Rules (Chem 234 Exam 1.)
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Chem 234 Exam 1Allows us to determine the molecule mass and the molecular formula of a
compound, as well as some of it's structural features - CORRECT
ANSWER-Mass Spectrometry
Tells us the kinds of functional groups a compound has - CORRECT
ANSWER-Infrared (IR) Spectroscopy
Provides information about the carbon-hydrogen framework of an organic
compound - CORRECT ANSWER-Nuclear magnetic resonance (NMR)
spectroscopy
A very small sample is placed in a mass spectrometer, where it is vaporized and
then ionized (electron removed from each molecule). Electron ionization (EI)
bombards the vaporized molecules with a beam of high-energy electrons which
knocks out an electron, producing a molecular ion (radical cation). The
bombardment injects so much kinetic energy that the molecular ions fragment.
All the positively charged fragments are drawn between two negatively charged
plates, which push them into a analyzer tube that is surrounded by a magnet.
The magnetic field deflects the positively charged fragments in a curved path
depending on mass-to-charge ratio (M/z). The particles with the same m/z can be
separated. The strength of the magnetic field is increased so progressively larger
m/z values are guided through - CORRECT ANSWER-Mass Spectroscopy
Typical beam strength in Mass spectroscopy - CORRECT ANSWER-70 electron
volts
a species with an unpaired electron and a positive charge - CORRECT
ANSWER-radical cation (molecular ion)
The path of a fragment with a smaller m/z will bend ____ than that of a heavier
fragment - CORRECT ANSWER-more
A graph of the relative abundance of each fragment plotted against it's m/z value
- CORRECT ANSWER-Mass Spectrum
, Seince the charge (z) of all fragments is essentially +1, m/z is the ____? -
CORRECT ANSWER-mass (m)
The peak with the highest m/z value is the _____? - CORRECT
ANSWER-molecular ion
The m/z value of the molecular ion (highest m/z) gives the _____ - CORRECT
ANSWER-molecular mass
Peaks with smaller m/z values -- represent positively charged fragments of the
molecular ion - CORRECT ANSWER-Fragment ion peaks
Tallest peak -- it has the greatest relative abundance because it is generally the
most stable positively charged fragment (assigned 100% abundance) -
CORRECT ANSWER-Base peak
The relative abundance of each of the other peaks is shown as a percentage of
the ____ - CORRECT ANSWER-base peak
When breaking bonds, resulting in primary carbocation and a primary radical is
____ favorable then ending with a methyl carbocation/radical - CORRECT
ANSWER-MORE
Tertiary carbocations is the _____ stable - CORRECT ANSWER-most
Weaker bonds will fragment first, and bonds that break to form more stable
fragments break in preference than those that form less stable fragments -
CORRECT ANSWER-Fragmentation rules
Allows possible molecular formulas to be determined from the m/z value of the
molecular ion - CORRECT ANSWER-Rule of 13
Dividing m/z value of the molecular ion by 13 to determine number of carbons -
CORRECT ANSWER-Base value
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