The molecular weight of ethylene glycol is 62.0689 when calculated using the atomic weights found in a standard periodic table, yet the molecular weight determined experimentally by high-resolution mass spectrometry is 62.0368. Explain the discrepancy.

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Hello everyone today. We have the following problem. When the molecular weight of acetone is calculated using the atomic weight found in the periodic table. The value would be 58.07891. However, the molecular weight that is obtained from high resolution mass spectrometer, we will give you a slightly different value which of the following statements explains this difference in weight so isolated in the question stem high resolution mass spectrometer. So we're going to abbreviate that as H R. M. S. High resolution mass spectrometer can give us isotopic composition such as 12 C, 13 C. Or one hydrogen or two hydrogen. We want to note that the atomic mass of elements in the periodic table are their isotopic masses and the relative abundance. So it's the averages of the different isotopes found. And so with that the answer is going to be a the mass of molecules with specific isotopic compositions can be detected and measured in high resolution mass spectrometry. And so with that we've answered the question. Ultimately, I hope this helped. And until next time.

The molecular weight of ethylene glycol is 62.0689 when calculated using the atomic weights found in a standard periodic table, yet the molecular weight determined experimentally by high-resolution mass spectrometry is 62.0368. Explain the discrepancy.

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Key Concepts

Molecular Weight Calculation

Isotopic Abundance

Mass Spectrometry