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Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
The structural formula illustrates the way the bonding takes place between the atoms of elements in a compound. The molecular formula shows the numbers of each atom in the compound. Responders may encounter the molecular formula along with the name; however, it is unlikely that they will see a structural formula in the field. As can be seen with the structural formula of carbon disulfide, there are two bonds between the sulfur and the carbon. This configuration of bonding is referred to as double bonding. Double bonds are very unstable; which is why carbon disulfide is so very flammable. Most compounds that have this carbon to carbon double bond are unstable. Triple bonds are even more unstable so these compounds are not usually shipped in transportation except for welding bottles of acetylene. Acetylene is the only commercially valuable triple-bonded material you are likely to encounter.
Analysis of Pesticide Residues by Chromatographic Techniques Coupled with Mass Spectrometry
Published in José L. Tadeo, Analysis of Pesticides in Food and Environmental Samples, 2019
Wan Jing, Jin Maojun, Jae-Han Shim, A.M. Abd El-Aty
The advantages of FI: compared to EI, FI is a softer ionization method. It only produces molecular ions, almost no fragment ions. The FI spectrum is very clean because there is no reagent background. FI source is suitable for the determination of the molecular weight of polymers and homologues. Combined with high-resolution mass spectrometry, the elemental composition and the molecular formula of the compound can be obtained. FI source is therefore very advantageous for the identification of the compound.
Properties and Characteristics of Water and Wastewater
Published in Donald R. Rowe, Isam Mohammed Abdel-Magid, Handbook of Wastewater Reclamation and Reuse, 2020
Donald R. Rowe, Isam Mohammed Abdel-Magid
The following review presents some basic aspects of chemistry that will help to understand the technology involved in the water and wastewater fields.2,4,18An element is a substance which cannot be changed into any simpler substances.An atom is the smallest unit of each of the elements. The atom consists of a positively charged nucleus containing protons and neutrons. Electrons occupy the extranuclear space. The nucleus is about 10−15 m in radius. The radius of the atom is about 10−10 m; thus the atom is mostly an empty space. Since the electron has a mass of 1/1837 of that of the proton, most of the mass of the atom is in its nucleus.Atomic weight (AW) of an element refers to the relative weight of the atoms of an element. Elements do not have atomic weights that are whole numbers because of the existence of isotopes.Gram atomic weight (GAW) of an element denotes the quantity of element in grams corresponding to the atomic weight.Atomic number of an atom is the number of protons in its nucleus.Mass number of an atom signifies the number of protons and neutrons.Molecular weight (MW) refers to the sum of the atomic weights of the atoms of a molecular formula.Molecular formula signifies a formula that describes both the number and types of atoms in a molecule.
Structural evaluation of coking component of West Bokaro coal of Indian origin
Published in International Journal of Coal Preparation and Utilization, 2022
Saswati Chakladar, Ashok Mohanty, Sujata Mandal, Sanchita Chakravarty
The peak at 679.52 in the spectrum is considered as the molecular ion peak (Fig. 8). On the basis of elemental analysis, FTIR, NMR, Raman analysis and XRD the molecular formula of the proposed compound has been coined to be C44H25NO5S which corresponds to an exact mass of 679.15, a difference of 0.37. The structure of the CC has been deduced as shown in Fig. 8. Further, the m/z isotopic pattern for above molecule predicted using ChemDraw Professional 15.0 software resulted in three peaks at m/z: 679.15 (100.0%), 680.15 (47.6%), 681.15 (11.1%), which is a good match to the mass spectrum obtained. Emphasizing on the evidence from Raman analysis, the proposed molecular structure of the CC isolated from West Bokaro coal is more graphitic as compared to the CC isolated from Jamadoba coal (Mohanty et al. 2019). In addition to the predominant molecular ion peak, two more peaks could be accounted for based on further truncations. The peak at 475.08 (difference of 0.25) corresponds to molecular formula of C29H17NO4S with an isotopic mass distribution of m/z: 475.08 (100.0%) and 476.09 (31.4%), matching perfectly with the spectrum. The corresponding truncated structure devoid of phenolic OH is shown in Fig. 8. The other prominent peak is at 413.14 (difference of 0.13) which has been evaluated to be the desulfonated and truncated version of the parent molecule corresponding to a molecular formula of C29H19NO2. The isotopic distribution of this molecule resulted in two peaks, one at 413.14 (100%) and another at 414.14 (31.4%) (Fig. 8).