Infrared Spectroscopy

Question 1

Technique that can be used in identifying the functional groups in a compound

Answer 1

Infrared Spectroscopy

Question 2

In IR spectrometer, light passes through a sample which cause changes in the _____ of a molecule

Answer 2

Vibrational motions

Question 3

IR spectrum has broad lines as compared to the sharp peaks in mass spectra. True or false

Answer 3

True

Question 4

Functional groups give one or two bands in the _____ region at 4000-1500 cm^-1.

Answer 4

Functional group region

Question 5

Refers to the area <1500 cm^-1 in IR spectrum

Answer 5

Fingerprint region

Question 6

Wavenumber is proportional to wavelength. True or false

Answer 6

False. Energy/Frequency

Question 7

In NMR spectroscopy, ___ and ___ are used to determine the number and type of H and C atoms, respectively in a molecule

Answer 7

1H NMR
13C NMR

Question 8

Instrumentation:
A. Sample dissolved in solvent and placed in magnetic field
B. RF generator irradiates sample with short pulse.of radiation, causing resonance
C. When nuclei fall back to lower energy state, detector measures the energy release and a spectrum is recorded

Question 9

Plot of intensity of pean against its chemical shift, measured in ppm

Answer 9

NMR Spectrum

Question 10

NMR absorptions relatively appear as sharp peaks.

Answer 10

True

Question 11

Most proton absorb between __

Answer 11

1-10 ppm

Question 12

Describes relative location of peaks

Answer 12

Upfield, downfield

Question 13

Used as external standard prior to NMR analysis

Answer 13

Tetramethylsilane (TMS)

Question 14

NMR plots ___ vs. ___

Answer 14

Intensity and chemical shift

Question 15

NMR performed to identify ___

Answer 15

Number and type of atoms

Question 16

___ and ___ used for resonance are two variables that characterize NMR

Answer 16

Applied magnetic field, frequency of radiation

Question 17

Energy in NMR

Answer 17

radiowaves or radiofrequency

Question 18

Nucleus is in ___ when it absorbs RF radiation and spin flips to a higher energy state

Answer 18

Resonance

Question 19

Equivalent protons do not split each others signal. ___ is observed for non equivalent protons on the same carbon or adjacent carbons

Answer 19

Spin-spin splitting

Question 20

Loosely held pi electrons can either shield (NMR signal appears ___) or deshield (NMR signal appears ___) a nucleus

Answer 20

Upfield, downfield

Question 21

IR plots ___ and ___

Answer 21

% transmittance and wavenumber

Question 22

IR is performed to identify __

Answer 22

Functional groups

Question 23

Recall general trend and important IR absorptions

Question 24

Recall general trend and important IR absorptions

Question 25

IR spectroscopy can be used for characterization of solid, liquid or gas samples

Answer 25

True

Question 26

Describe sample preparation for the ff samples

Solids
Liquids
Gas

Answer 26

Mull, run in, case film, pressed pellet
Sandwiched using purified alkali halides like NaCl
Sample cells is made up of NaCl and KBr

Question 27

IR soectrum has broad lines compared to sharo peaks in mass spectra