Chemical analysis Flashcards
State some analytical methods
- Chemical tests
- Elemental composition
- Mass spectrometry
- UV-VIS spectroscopy
- Infrared spectroscopy
- Nuclear magnetic resonance spectroscopy
What is IR spectroscopy?
- Identifies functional groups
~ Bonds absorb light with a frequency that corresponds to a particular vibration
How is nuclear magnetic resonance interpreted?
- Looking at number of signals
- Chemical shift
- Integration
- Coupling
What is the nuclear spin when the number of neutrons/protons is:
- Even/Even
- Even/odd or odd/even
- Odd/Odd
- 0
- Half integer (1/2, 3/2…..)
- Integer (1,2…)
Describe chemical shifts
- X-axis on the NMR spectrum
- Magnetic field experienced by a nucleus depends on the electrons surrounding it
LOOK AT H1 CHEMICAL SHIFTS
LOOK AT H1 CHEMICAL SHIFTS
LOOK AT C13 CHEMICAL SHIFTS
LOOK AT C13 CHEMICAL SHIFTS
What are the features of ethanol?
• No symmetry
• Free rotation of bonds
- 2 Carbon environments: 3 Hydrogen environments
What does the integration allow us to determine?
- Number of H in each environment
What are the features of Toluene?
- Symmetric molecule
* 5 carbon environments: 4 hydrogen environments
What is coupling and where is it most commonly observed?
• Interaction between nuclei
- Most commonly observed for H1-H1, C13 are decoupled
Spin of neighbour can O____ or add to external field
• Oppose
The couple pattern: Triplet has ……..
• 2 identical neighbours
True or false: Ethanol has free rotation
TRUE
