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Experiment #4Experiment Title: Mass SpectrometryStudent Name: Student Number: Section Number: 0116Date the experiment was performed: March/14th/2013Date the lab report was submitted: March/21st/2013Submitted to Tae Hun KimPre-lab/10Purpose/5Graph/10Results /30Accuracy/5Summary/3References/2Experimental Technique/10Report Presentation/10Writing Initiative/15
Introduction:Mass spectrometry is a technique that is used to confirm or identify chemical species. Theinstrument used in mass spectrometry is known as a mass spectrometer. It is designed to ionize gaseous molecules, separate the ions produced on the basis of their mass-to-charge ratio and record the relative number of different ions produced. J.J. Thompson developed the mass spectrometer in 1911, at Cambridge. The data obtained from the mass spectrometer is called mass spectrum, which is a plot of the mass/charge ratio (m/q) and the relative abundance % of anion. In mass spectrometer, a given unknown sample is ionized through collisions with electrons. The ions thus produced are accelerated by passing through two plates with a large potential difference, according to ½ mv2= qV (m=mass of the ion in kg, q = the charge in coulombs, V = potential of the ions accelerating plates in volts, and v = the velocity of particles in m/s). The accelerated ions are then subjected to a magnetic field B (measured in tesla), which deflects the ions along a circular path of radius r given by r = mv/qB. The above two equations give a rearranged equation m/q = B2r2/2V. This equation is further rearranged to obtain M/Z (amu/electron charge) which implies that only ions with a given mass/charge ratio will arrive at the detector. By varying the magnetic field B or the accelerating voltage V, all the values of m/q will be scanned to obtain the spectrum of ions. This spectrum, which is assumed to largely contain single charge ions, is then analyzed to identify the unknown species.Purpose:In this experiment, a data obtained from similar kind of instrument was used to identify an unknown chemical species. The purpose of the experiment was to understand the working of the mass spectrometer and to get familiarized with the analysis of mass spectrum to obtain the identity of the unknown chemical species.