Calculating Chemical Shift: How do magnetic fields affect NMR frequencies?

AI Thread Summary
In the discussion on calculating chemical shift in NMR, a CH2 group's peak is noted at 9.81 ppm with a magnetic field of 9.4 T and a magnetogyric ratio of 26.75 × 10^7 rad s^-1T^-1. The calculated Larmor frequency for the protons is approximately 400 MHz. The chemical shift formula is applied, but the user struggles with the subsequent calculations to find the sample frequency. The final frequency calculation appears incorrect, indicating a need for clarification on the relevant equations and proper citation of sources. Accurate understanding of these concepts is crucial for interpreting NMR spectra effectively.
Lily Wright
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Homework Statement


In an NMR spectrum a CH2 group has a peak centred at 9.81 ppm. What is the shift in Larmor frequency of the protons from that of an unshielded proton if the spectrometer magnetic field is 9.4 T? The magnetogyric ratio of an unshielded proton is γH = 26.75 × 107 rad s-1T-1

2. The attempt at a solution
So 26.75 × 107 rad s-1T-1 x 9.4 T = 2.51 x 109 rad s-1
x 0.159155 = 4.00 x 109 Hz
/106 = 400 MHz

Then I don't really know what to do
Chemical shift = v(sample)-v(reference)/v(reference)
9.81ppm = 106 x (v(sample)- 4 x 10-9/4 x 10-9)
3924 = 106 x (v(sample) x 10-6 - 400)
4324 MHz for the sample frequency which I'm sure is wrong.
 
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