Experiment 1- IR Spectroscopy Flashcards
What is the relationship between wavelength and energy?
Inverse
What does spectroscopy examine?
Interaction between electromagnetic radiation and matter.
What molecule is responsible from absorbing most of the UV light on earth?
Ozone (O3)
What happens to the wavelength of the light that’s absorbed when the molecule is more conjugated?
Light is absorbed at a higher wavelength.
What does NMR involve?
How the nuclei of atoms like hydrogen and carbon-13 are excited by radio waves.
What is the main purpose of this lab?
To see how different functional groups absorb infrared radiation.
What type of spectroscopy is used to determine the types of functional groups present in molecules?
Infrared Spectroscopy
What is the range of IR frequencies that causes bonds to vibrate?
400-4000 cm^-1.
What is another name for cm^-1?
Wavenumber; number of waves per cm.
What happens when bonds absorb IR radiation ?
The bonds vibrate, which can be categorized into stretching and bending modes.
What does it mean for the absorption process to be quantized?
A particular bond or functional group is very specific to the wavelength of IR radiation that it will absorb.
What is the formula for Hooke’s Law?
V= (1/2πc) . √(f/u)
V= frequency of energy
Where U= m1m2/m1+m2 (reduced mass)
C= speed of light in m/s
F= force constant
What is the relationship between the frequency and the reduced mass?
It is inversely proportional to the root of the reduced mass: the larger the reduced mass, the lower the frequency of IR radiation.
What is the relationship between bond strength and frequency of vibration?
Direct; the stronger the bond, the greater the frequency.
What are the axis present in IR SPECTRA?
% Transmittance on the y-axis and the frequencies in wave numbers on the x-axis.
What regions can sp3 hybridized C-H bonds be found?
Less than 3000 cm^-1.
What regions can sp2 hybridized C-H bonds be found?
3000-3150 cm^-1.
What regions can sp hybridized C-H bonds be found?
3250-3350 cm^-1.
What are the important regions that double bonds, triple bonds, and single bonds can be found respectively?
CC/CN/CO Double: 1550-1850 cm^-1.
CC/CN Triple: 2100-2300 cm^-1.
CC/CH/CN Single: 2850-3600 cm^-1.
What happens if a sample does not absorb a particular range of frequencies?
All the radiation passes through and the % transmittance will be 100%.
What is the range of the fingerprint region?
400-1500 cm^-1.
