A chemist is evaluating a proton NMR spectrum taken on a 300 MHz NMR spectrometer.She wishes to determine the chemical shift in ppm of a singlet that appears at 1140 Hz from TMS.What is the chemical shift in ppm?
A) 0.26 ppm
B) 3.8 ppm
C) 7.6 ppm
D) 300 ppm
E) None of the above.

Question

Quizplus · Accepted Answer

To convert Hz to ppm, we use the formula:
chemical shift (ppm) = (observed frequency - reference frequency) / reference frequency
In this case, the observed frequency is 1140 Hz and the reference frequency is 300 MHz (which is equivalent to 300000000 Hz). Thus, the chemical shift in ppm is:
(1140 - 0) / 300000000 = 0.0000038 = 3.8 ppm. Therefore, the best choice is B.

A Chemist Is Evaluating a Proton NMR Spectrum Taken on a 300