What technique is commonly used to identify the molecular weight of organic compounds?

What technique is commonly used to identify the molecular weight of organic compounds?

• A. Nuclear Magnetic Resonance (NMR)
• B. Infrared Spectroscopy (IR)
• C. Mass Spectrometry
• D. Gas Chromatography (GC)

Answer: (C)

Mass Spectrometry is a powerful analytical technique specifically designed for determining the molecular weight of organic compounds. This technique works by ionizing chemical species and sorting the ions based on their mass-to-charge ratio. In the mass spectrometer, molecules are fragmented, and the resulting pieces can be analyzed to provide both the molecular weight and structural information of the compounds. When a sample is introduced into the mass spectrometer, it is vaporized and ionized, producing charged particles. These ions are then accelerated, entering a flight tube where their mass-to-charge ratios are measured. The resulting mass spectrum displays peaks that correspond to different ions, with the most prominent peak typically reflecting the molecular ion, which corresponds to the compound's molecular weight. While techniques like Nuclear Magnetic Resonance (NMR) and Infrared Spectroscopy (IR) provide significant structural information about organic compounds, they do not give direct measurements of molecular weight. Gas Chromatography (GC) is often used for separating mixtures of compounds, but it also does not measure molecular weight directly; instead, it can be coupled with Mass Spectrometry to provide that information. Thus, Mass Spectrometry stands out as the definitive method for determining molecular weight in organic chemistry laboratories and research.

Mass Spectrometry is a powerful analytical technique specifically designed for determining the molecular weight of organic compounds. This technique works by ionizing chemical species and sorting the ions based on their mass-to-charge ratio. In the mass spectrometer, molecules are fragmented, and the resulting pieces can be analyzed to provide both the molecular weight and structural information of the compounds.

When a sample is introduced into the mass spectrometer, it is vaporized and ionized, producing charged particles. These ions are then accelerated, entering a flight tube where their mass-to-charge ratios are measured. The resulting mass spectrum displays peaks that correspond to different ions, with the most prominent peak typically reflecting the molecular ion, which corresponds to the compound's molecular weight.

While techniques like Nuclear Magnetic Resonance (NMR) and Infrared Spectroscopy (IR) provide significant structural information about organic compounds, they do not give direct measurements of molecular weight. Gas Chromatography (GC) is often used for separating mixtures of compounds, but it also does not measure molecular weight directly; instead, it can be coupled with Mass Spectrometry to provide that information.

Thus, Mass Spectrometry stands out as the definitive method for determining molecular weight in organic chemistry laboratories and research.