IR Flashcards
T/F: ER has properties of waves and particles
T
Relationship btwn wavelength and freq
inverse. c=wavelength(freq)
Relationship btwn energy of photon and freq
proportional. E=hv
IR gives info abt…
IR
NMR gives info abt…
chemical env/connectivity
T/F: energy exists as a continuum
F, delta E is quantize
Which has a larger delta E, C-H or C-O?
C-H
relationship btwn wavenumber and force constant (bond strength)
proportional
relationship btwn wavenumber and mass
inverse
what factors affect wavenumber
mass, resonance, hybridization, bond strength
effect of mass on wavenumber
smaller = higher wavenumber
effect of bond strength on wavenumber
the stronger the bond = higher wavenumber
order for wavenumber
X-H > triple>double>single
effect of hybridization on wavenumber
sp = highest wavenumber
ring strain inc bond strength of C=O on a ring
non-integer hybridization
effect on resonance on wavenumber
more resonance = lower wavenumber
factors impacting signal intensity
bond polarity, number of identical bonds
effect of bond polarity on intensity
the more polar, the more intense
effect of number of bonds at that freq
the more bonds, the more intense
T/F: symmetrical molecules show up on an IR
F; symmetry is IR silent
T/F: IMF can’t change bond strength
F; hydrogen bonding makes a broader signal bc it weakens the bond (OH and NHs)
how many signals do secondary amines have
1
how many signals do primary amines have
2
why do primary amines have 2 signals?
NH2 has 2 stretching modes
what does mass spec useful for
determining molecular weight of molecule
how is mass spec done?
using a high-energy electron to strike a vaporized molecule, energy-rich molecule ejects an electron and is now a radical cation which gets detected
T/F: the larger the mass, the more it gets deflected
F
T/F: bp can sometimes be molecular ion peak
T
Br on mass spec
M+. and (M+2)+. are 1:1 in height
Cl on mass spec
M+. and (M+2)+. are 3:1 in height
weight of benzene
78
