Lab 8.
Prelab Questions.
Questions you NEED
to answer in a written form (in your
lab notebook) before
the Lab.
Estimate the difference in
populations between two nuclear spin orinetations mI
= +1/2 and mI = -1/2 for a free proton at room
temperature and T = 77 K in a magnetic field B0 =
4T.
- Sketch the 1H spectra of
- ethanol
- 2-propanol
- benzene
- acetone
1,4 -hydroxybenzene
(hydroquinone)
- 1,2 - hydroxybenzene (cathecol)
- perylene
- What will change and what will remain the same in these
spectra when you use a 60 MHz or a 200 MHz spectrometers?
- You use a 200 MHz NMR
spectrometer and observe two lines separated by 1 ppm.
What is the frequency shift between them
in Hz?
- You are asked to
prepare 5 mL of acetate/acetic acid (pKa =
4.75 @25°C) buffer at pH = 4.5 and adjust its ionic
strength to 2M using NaCl; how do you proceed?
What kind of questions you MAY be
asked before the Lab.
- What are the main components of an NMR spectrometer?
- Why is there a rush among scientists to get NMR
spectrometers of higher and higher working frequencies?
What is good and what is bad about it?
- Does the coalescence temperature for spin exchange depend
on the frequency of your spectrometer?
- What is a magic spinning angle and why it helps?
- Can NMR of paramagnetic species be employed? What is a
problem?
- What is a relaxation time? What is a difference between T1
and T2?
Last updated 03/22/99.
Email: snsm@nmsu.edu