15 Analytical methods Flashcards

(18 cards)

1
Q

does UV/visible spectrum require a sample

A

yes

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2
Q

what does a UV spectrum show

A

broad bands rather than sharp lines

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3
Q

what happens in rotational molecular absorption spectra

A

dipoles rotate absorbing energy

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4
Q

what happens in vibrational molecular absorption spectra

A

bonds absorb energy and vibrate

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5
Q

what happens in electronic molecular absorption spectra

A

molecule changes electron configuration

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6
Q

what do most molecules do at room temp

A

have vibrational and electronic states

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7
Q

what happens when polychromatic light interacts with molecules of a compound

A

some of the molecules will absorb the radiation

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8
Q

what happens when certain types of electrons are excited to a higher energy state

A

there is an increase in the energy levels of rotational and vibrational states

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9
Q

what is beers law

A

the intensity of a beam of parallel monochromatic light decreases exponentially with the number of absorbed molecules

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10
Q

what does light scattering cause

A

absorbance>true

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11
Q

where do errors with light scattering increase

A

at shorter wavelengths

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12
Q

does IR have more or less energy than UV/visible light

A

less

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13
Q

what does absorption of IR transition in

A
  • vibrational energy levels
  • rotational energy levels
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14
Q

what must absorption of IR cause

A

a change in the dipole moment of the molecule

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15
Q

what is polymorphism

A

the ability of a compound the adopt more than one three dimensional structure

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16
Q

what can IR spectroscopy identify

A

intramolecular bond stretches via change in dipole

17
Q

what can HPLC methods be used for

A

to identify multiple components in systems as well as structurally similar ones

18
Q

what can X-ray diffraction techniques identify

A

molecular structure