Question

The chemical shift of the protons in acetone is δ2.06. How many hertz downfield from TMS will the resonance appear in a spectrum taken on a spectrometer operating at 300 MHz?

A. 300 Hz

B. 618 Hz

C. 3000 Hz

D. 6.18 x 10⁸ Hz

Answer 1

The correct answer is Option B. The resonance will appear downfield by 618 Hz.

Step-by-step explanation:

In NMR spectroscopy, the chemical shift is given in parts per million (ppm) and represents the frequency difference between the resonance of a particular proton and a reference compound, most commonly tetramethylsilane (TMS). To calculate the frequency downfield from TMS in hertz, we can use the formula:

Frequency (Hz) = Chemical Shift (ppm) x Spectrometer Frequency (MHz)

In this case, the chemical shift is given as δ2.06, and the spectrometer is operating at 300 MHz. Therefore, the resonance will appear

downfield from TMS by 618 Hz (B).