Virtual Labs

Nuclear Magnetic Resosnance Spectrocopy and Evaulation of Simple 1H NMR Spectra of Select Organic Compounds

1. When an external magnetic field is applied, what happens to the protons in the sample?

a: All protons align with the field. Explanation

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b: All protons align opposite to the field. Explanation

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c: Some protons align with the field and some align opposite to it. Explanation

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d: All protons assume a random orientation. Explanation

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2. Which of the following is false about NMR experiment?

a: The energy required to flip the spin of a proton is in the infrared region of the electromagnetic spectrum. Explanation

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b: The energy difference between the two spin states depends on the strength of the magnetic field. Explanation

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c: When energy absorption occurs, the nuclei are said to be in resonance with the electromagnetic radiation. Explanation

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d: When a proton is aligned with the magnetic field, its energy is lower than when it is aligned against the magnetic field. Explanation

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3. What is the value of the chemical shift δ for an absorption at 1800 Hz from tetramethylsilane (TMS) using an NMR spectrometer with an operating frequency of 300 MHz?

a: 1.66 ppm Explanation

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b: 16.6 ppm Explanation

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c: 6.0 ppm Explanation

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d: 4.0 ppm Explanation

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4. Which of the following compounds has the MOST deshielded methyl protons?

a: tetramethylsilane Explanation

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b: methyl fluoride Explanation

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c: methanol Explanation

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d: methylamine Explanation

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5. How many signals would the following molecule show in its 1H NMR spectrum? Question Image

a: 5 Explanation

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b: 1 Explanation

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c: 6 Explanation

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d: 3 Explanation

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