Structure Determination Flashcards
How does Infrared spectroscopy detect different functional groups?
By the vibrations or their bonds
How do double bonds relate to resonance structures and stability?
More double bonds = more resonance structures = more stability
What is Infrared spectroscopy used for?
Determining which functional groups are present
If a molecule absorbs in the UV between 200-400 nm, what does this mean?
It has conjugated double bonds
What must occur a compound to raise an energy level?
The energy of radiation must be equal to the energy difference between the energy levels E1 and E2
Do high energy structures absorb at a high or low wavelength?
A low wavelength
What wavenumber (cm^-1) will C=C bonds absorb at?
1600 cm^-1
What wavenumber (cm^-1) will O-H bonds absorb at?
A very broad peak near 3400 cm^-1
What does the Beer-Lambert law state?
The absorbance of a compound varies in a linear fashion with concentration
How does the energy of a wave correspond to its frequency?
The higher the frequency, the higher the energy
What are conjugated double bonds?
Double bonds alternating with single bonds
If a molecule has conjugated double bonds, what wavelength will it absorb?
200-400nm
What wavenumber (cm^-1) will C=O bonds absorb at?
1700 cm^-1
What does mass spectroscopy help us to find?
The molecular formula of a molecule
What is the formula for Beer’s Law?
A = εcl
Where
A = absorbance
ε = molar absorptivity (specific to the molecule)
c = concentration
l = the distance the light travels through the sample
