Resumen de A Strategy for Incorporating Hands-On GC-MS into the General Chemistry Lecture and Laboratory Courses
Perry C. Reeves, Kim L. Pamplin
Simple laboratory experiments employing mass spectrometry can be used to clarify the differences between the masses of the various isotopes of an element and the atomic mass of the element. As an introductory experiment, students use the GC-MS to obtain spectra of the various halobenzenes. This vividly illustrates the differences in isotopic distributions of the halogens and the complications these differences present in calculating molar masses of compounds. The isotopic distribution of iron is then obtained from the mass spectrum of Fe(CO)5, a volatile liquid, and the students calculate the atomic mass of iron from this data. If the spectrometer is equipped for injection of volatile solids, the mass spectra of other volatile metal carbonyls (chromium, molybdenum, tungsten, etc.) can be obtained and their atomic masses calculated. Alternately, data from the NIST (National Institute for Standards and Technology) mass spectral database can be used.
