1.
Jmol
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Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D
2.
ChemSpider
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ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The search can be used to widen or restrict already found results, structure searching on mobile devices can be done using free apps for iOS and for the Android. The ChemSpider database has been used in combination with text mining as the basis of document markup. The result is a system between chemistry documents and information look-up via ChemSpider into over 150 data sources. ChemSpider was acquired by the Royal Society of Chemistry in May,2009, prior to the acquisition by RSC, ChemSpider was controlled by a private corporation, ChemZoo Inc. The system was first launched in March 2007 in a release form. ChemSpider has expanded the generic support of a database to include support of the Wikipedia chemical structure collection via their WiChempedia implementation. A number of services are available online. SyntheticPages is an interactive database of synthetic chemistry procedures operated by the Royal Society of Chemistry. Users submit synthetic procedures which they have conducted themselves for publication on the site and these procedures may be original works, but they are more often based on literature reactions. Citations to the published procedure are made where appropriate. They are checked by an editor before posting. The pages do not undergo formal peer-review like a journal article. The comments are moderated by scientific editors. The intention is to collect practical experience of how to conduct useful chemical synthesis in the lab, while experimental methods published in an ordinary academic journal are listed formally and concisely, the procedures in ChemSpider SyntheticPages are given with more practical detail. Comments by submitters are included as well, other publications with comparable amounts of detail include Organic Syntheses and Inorganic Syntheses
3.
European Chemicals Agency
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ECHA is the driving force among regulatory authorities in implementing the EUs chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and it is located in Helsinki, Finland. The Agency, headed by Executive Director Geert Dancet, started working on 1 June 2007, the REACH Regulation requires companies to provide information on the hazards, risks and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most commonly used substances have been registered, the information is technical but gives detail on the impact of each chemical on people and the environment. This also gives European consumers the right to ask whether the goods they buy contain dangerous substances. The Classification, Labelling and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU. This worldwide system makes it easier for workers and consumers to know the effects of chemicals, companies need to notify ECHA of the classification and labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100000 substances, the information is freely available on their website. Consumers can check chemicals in the products they use, Biocidal products include, for example, insect repellents and disinfectants used in hospitals. The Biocidal Products Regulation ensures that there is information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation, the law on Prior Informed Consent sets guidelines for the export and import of hazardous chemicals. Through this mechanism, countries due to hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have effects on human health and the environment are identified as Substances of Very High Concern 1. These are mainly substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment, other substances considered as SVHCs include, for example, endocrine disrupting chemicals. Companies manufacturing or importing articles containing these substances in a concentration above 0 and they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy, once a substance has been officially identified in the EU as being of very high concern, it will be added to a list. This list is available on ECHA’s website and shows consumers and industry which chemicals are identified as SVHCs, Substances placed on the Candidate List can then move to another list
4.
International Chemical Identifier
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Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary. The continuing development of the standard has supported since 2010 by the not-for-profit InChI Trust. The current version is 1.04 and was released in September 2011, prior to 1.04, the software was freely available under the open source LGPL license, but it now uses a custom license called IUPAC-InChI Trust License. Not all layers have to be provided, for instance, the layer can be omitted if that type of information is not relevant to the particular application. InChIs can thus be seen as akin to a general and extremely formalized version of IUPAC names and they can express more information than the simpler SMILES notation and differ in that every structure has a unique InChI string, which is important in database applications. Information about the 3-dimensional coordinates of atoms is not represented in InChI, the InChI algorithm converts input structural information into a unique InChI identifier in a three-step process, normalization, canonicalization, and serialization. The InChIKey, sometimes referred to as a hashed InChI, is a fixed length condensed digital representation of the InChI that is not human-understandable. The InChIKey specification was released in September 2007 in order to facilitate web searches for chemical compounds and it should be noted that, unlike the InChI, the InChIKey is not unique, though collisions can be calculated to be very rare, they happen. In January 2009 the final 1.02 version of the InChI software was released and this provided a means to generate so called standard InChI, which does not allow for user selectable options in dealing with the stereochemistry and tautomeric layers of the InChI string. The standard InChIKey is then the hashed version of the standard InChI string, the standard InChI will simplify comparison of InChI strings and keys generated by different groups, and subsequently accessed via diverse sources such as databases and web resources. Every InChI starts with the string InChI= followed by the version number and this is followed by the letter S for standard InChIs. The remaining information is structured as a sequence of layers and sub-layers, the layers and sub-layers are separated by the delimiter / and start with a characteristic prefix letter. The six layers with important sublayers are, Main layer Chemical formula and this is the only sublayer that must occur in every InChI. The atoms in the formula are numbered in sequence, this sublayer describes which atoms are connected by bonds to which other ones. Describes how many hydrogen atoms are connected to each of the other atoms, the condensed,27 character standard InChIKey is a hashed version of the full standard InChI, designed to allow for easy web searches of chemical compounds. Most chemical structures on the Web up to 2007 have been represented as GIF files, the full InChI turned out to be too lengthy for easy searching, and therefore the InChIKey was developed. With all databases currently having below 50 million structures, such duplication appears unlikely at present, a recent study more extensively studies the collision rate finding that the experimental collision rate is in agreement with the theoretical expectations. Example, Morphine has the structure shown on the right, as the InChI cannot be reconstructed from the InChIKey, an InChIKey always needs to be linked to the original InChI to get back to the original structure
5.
Simplified molecular-input line-entry system
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The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specification was initiated in the 1980s. It has since modified and extended. In 2007, a standard called OpenSMILES was developed in the open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. The Environmental Protection Agency funded the project to develop SMILES. It has since modified and extended by others, most notably by Daylight Chemical Information Systems. In 2007, a standard called OpenSMILES was developed by the Blue Obelisk open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, in July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is generally considered to have the advantage of being slightly more human-readable than InChI, the term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings. However, the term SMILES is also used to refer to both a single SMILES string and a number of SMILES strings, the exact meaning is usually apparent from the context. The terms canonical and isomeric can lead to confusion when applied to SMILES. The terms describe different attributes of SMILES strings and are not mutually exclusive, typically, a number of equally valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol, algorithms have been developed to generate the same SMILES string for a given molecule, of the many possible strings, these algorithms choose only one of them. This SMILES is unique for each structure, although dependent on the algorithm used to generate it. These algorithms first convert the SMILES to a representation of the molecular structure. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database, there is currently no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, and these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES
6.
Chemical formula
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These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH
7.
Density
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The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume, ρ = m V, where ρ is the density, m is the mass, and V is the volume. In some cases, density is defined as its weight per unit volume. For a pure substance the density has the numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity, osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. Thus a relative density less than one means that the floats in water. The density of a material varies with temperature and pressure and this variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object, increasing the temperature of a substance decreases its density by increasing its volume. In most materials, heating the bottom of a results in convection of the heat from the bottom to the top. This causes it to rise relative to more dense unheated material, the reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is a property in that increasing the amount of a substance does not increase its density. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass, upon this discovery, he leapt from his bath and ran naked through the streets shouting, Eureka. As a result, the term eureka entered common parlance and is used today to indicate a moment of enlightenment, the story first appeared in written form in Vitruvius books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time, from the equation for density, mass density has units of mass divided by volume. As there are units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per metre and the cgs unit of gram per cubic centimetre are probably the most commonly used units for density.1,000 kg/m3 equals 1 g/cm3. In industry, other larger or smaller units of mass and or volume are often more practical, see below for a list of some of the most common units of density
8.
Melting point
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The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances, melting and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs. Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can also be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
9.
Boiling point
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The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the environmental pressure. A liquid in a vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at high pressure has a boiling point than when that liquid is at atmospheric pressure. For a given pressure, different liquids boil at different temperatures, for example, water boils at 100 °C at sea level, but at 93.4 °C at 2,000 metres altitude. The normal boiling point of a liquid is the case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level,1 atmosphere. At that temperature, the pressure of the liquid becomes sufficient to overcome atmospheric pressure. The standard boiling point has been defined by IUPAC since 1982 as the temperature at which boiling occurs under a pressure of 1 bar, the heat of vaporization is the energy required to transform a given quantity of a substance from a liquid into a gas at a given pressure. Liquids may change to a vapor at temperatures below their boiling points through the process of evaporation, evaporation is a surface phenomenon in which molecules located near the liquids edge, not contained by enough liquid pressure on that side, escape into the surroundings as vapor. On the other hand, boiling is a process in which molecules anywhere in the liquid escape, a saturated liquid contains as much thermal energy as it can without boiling. The saturation temperature is the temperature for a corresponding saturation pressure at which a liquid boils into its vapor phase, the liquid can be said to be saturated with thermal energy. Any addition of energy results in a phase transition. If the pressure in a system remains constant, a vapor at saturation temperature will begin to condense into its liquid phase as thermal energy is removed, similarly, a liquid at saturation temperature and pressure will boil into its vapor phase as additional thermal energy is applied. The boiling point corresponds to the temperature at which the pressure of the liquid equals the surrounding environmental pressure. Thus, the point is dependent on the pressure. Boiling points may be published with respect to the NIST, USA standard pressure of 101.325 kPa, at higher elevations, where the atmospheric pressure is much lower, the boiling point is also lower. The boiling point increases with increased pressure up to the critical point, the boiling point cannot be increased beyond the critical point. Likewise, the point decreases with decreasing pressure until the triple point is reached
10.
Aqueous solution
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An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant chemical formula, for example, a solution of table salt, or sodium chloride, in water would be represented as Na+ + Cl−. The word aqueous means pertaining to, related to, similar to, as water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Substances that are hydrophobic often do not dissolve well in water, an example of a hydrophilic substance is sodium chloride. Acids and bases are aqueous solutions, as part of their Arrhenius definitions, the ability of a substance to dissolve in water is determined by whether the substance can match or exceed the strong attractive forces that water molecules generate between themselves. If the substance lacks the ability to dissolve in water the molecules form a precipitate, reactions in aqueous solutions are usually metathesis reactions. Metathesis reactions are another term for double-displacement, that is, when a cation displaces to form a bond with the other anion. The cation bonded with the latter anion will dissociate and bond with the other anion, aqueous solutions that conduct electric current efficiently contain strong electrolytes, while ones that conduct poorly are considered to have weak electrolytes. Those strong electrolytes are substances that are ionized in water. Nonelectrolytes are substances that dissolve in water yet maintain their molecular integrity, examples include sugar, urea, glycerol, and methylsulfonylmethane. When writing the equations of reactions, it is essential to determine the precipitate. To determine the precipitate, one must consult a chart of solubility, soluble compounds are aqueous, while insoluble compounds are the precipitate. Remember that there may not always be a precipitate, when performing calculations regarding the reacting of one or more aqueous solutions, in general one must know the concentration, or molarity, of the aqueous solutions. Solution concentration is given in terms of the form of the prior to it dissolving. Metal ions in aqueous solution Solubility Dissociation Acid-base reaction theories Properties of water Zumdahl S.1997, 4th ed. Boston, Houghton Mifflin Company
11.
Occupational safety and health
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These terms of course also refer to the goals of this field, so their use in the sense of this article was originally an abbreviation of occupational safety and health program/department etc. The goals of occupational safety and health programs include to foster a safe, OSH may also protect co-workers, family members, employers, customers, and many others who might be affected by the workplace environment. In the United States, the occupational health and safety is referred to as occupational health and occupational and non-occupational safety. In common-law jurisdictions, employers have a common law duty to take care of the safety of their employees. As defined by the World Health Organization occupational health deals with all aspects of health, Health has been defined as a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity. Occupational health is a field of healthcare concerned with enabling an individual to undertake their occupation. Health has been defined as It contrasts, for example, with the promotion of health and safety at work, since 1950, the International Labour Organization and the World Health Organization have shared a common definition of occupational health. It was adopted by the Joint ILO/WHO Committee on Occupational Health at its first session in 1950, the concept of working culture is intended in this context to mean a reflection of the essential value systems adopted by the undertaking concerned. Such a culture is reflected in practice in the systems, personnel policy, principles for participation, training policies. Professionals advise on a range of occupational health matters. The research and regulation of safety and health are a relatively recent phenomenon. As labor movements arose in response to concerns in the wake of the industrial revolution. The initial remit of the Inspectorate was to police restrictions on the hours in the textile industry of children. The commission sparked public outrage resulted in the Mines Act of 1842. Otto von Bismarck inaugurated the first social insurance legislation in 1883, similar acts followed in other countries, partly in response to labor unrest. Although work provides many economic and other benefits, an array of workplace hazards also present risks to the health. Personal protective equipment can protect against many of these hazards. Physical hazards affect many people in the workplace, Falls are also a common cause of occupational injuries and fatalities, especially in construction, extraction, transportation, healthcare, and building cleaning and maintenance
12.
Safety data sheet
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A safety data sheet, material safety data sheet, or product safety data sheet is an important component of product stewardship, occupational safety and health, and spill-handling procedures. SDS formats can vary from source to source within a country depending on national requirements, SDSs are a widely used system for cataloging information on chemicals, chemical compounds, and chemical mixtures. SDS information may include instructions for the use and potential hazards associated with a particular material or product. The SDS should be available for reference in the area where the chemicals are being stored or in use, there is also a duty to properly label substances on the basis of physico-chemical, health and/or environmental risk. Labels can include hazard symbols such as the European Union standard symbols, a SDS for a substance is not primarily intended for use by the general consumer, focusing instead on the hazards of working with the material in an occupational setting. It is important to use an SDS specific to country and supplier, as the same product can have different formulations in different countries. The formulation and hazard of a product using a name may vary between manufacturers in the same country. Safety data sheets have made an integral part of the system of Regulation No 1907/2006. The SDS must be supplied in a language of the Member State where the substance or mixture is placed on the market. The 16 sections are, SECTION1, Identification of the substance/mixture, relevant identified uses of the substance or mixture and uses advised against 1.3. Details of the supplier of the safety data sheet 1.4, Emergency telephone number SECTION2, Hazards identification 2.1. Classification of the substance or mixture 2.2, Other hazards SECTION3, Composition/information on ingredients 3.1. Mixtures SECTION4, First aid measures 4.1, Description of first aid measures 4.2. Most important symptoms and effects, both acute and delayed 4.3, indication of any immediate medical attention and special treatment needed SECTION5, Firefighting measures 5.1. Special hazards arising from the substance or mixture 5.3, advice for firefighters SECTION6, Accidental release measure 6.1. Personal precautions, protective equipment and emergency procedures 6.2, methods and material for containment and cleaning up 6.4. Reference to other sections SECTION7, Handling and storage 7.1, conditions for safe storage, including any incompatibilities 7.3. Specific end use SECTION8, Exposure controls/personal protection 8.1, Exposure controls SECTION9, Physical and chemical properties 9.1
13.
GHS hazard pictograms
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Hazard pictograms form part of the international Globally Harmonized System of Classification and Labelling of Chemicals. Two sets of pictograms are included within the GHS, one for the labelling of containers and for workplace hazard warnings, either one or the other is chosen, depending on the target audience, but the two are not used together. The two sets of use the same symbols for the same hazards, although certain symbols are not required for transport pictograms. Transport pictograms come in variety of colors and may contain additional information such as a subcategory number. It has still to be implemented by the European Union in 2009, the following pictograms are included in the Worldwide Model Using but have not been incorporated into the GHS, ICZ and Catwallsh Hazcom Labelling because of the nature of the hazards. Globally Harmonized System of Classification and Labelling of Chemicals, New York and Geneva, United Nations,2007, ISBN 978-92-1-116957-7, ST/SG/AC. 10/30/Rev. Model Regulations, New York and Geneva, United Nations,2007, ISBN 978-92-1-139120-6, manual of Tests and Criteria, New York and Geneva, United Nations,2002, ISBN 92-1-139087-7, ST/SG/AC. 10/11/Rev.4 GHS pictogram gallery from the United Nations Economic Commission for Europe
14.
Flash point
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The flash point is the lowest temperature at which vapours of a volatile material will ignite, when given an ignition source. The flash point may sometimes be confused with the autoignition temperature, the fire point is the lowest temperature at which the vapor will keep burning after being ignited and the ignition source removed. The fire point is higher than the point, because at the flash point the vapor may be reliably expected to cease burning when the ignition source is removed. The flash point is a characteristic that is used to distinguish between flammable liquids, such as petrol, and combustible liquids, such as diesel. It is also used to characterize the fire hazards of liquids, all liquids have a specific vapor pressure, which is a function of that liquids temperature and is subject to Boyles Law. As temperature increases, vapor pressure increases, as vapor pressure increases, the concentration of vapor of a flammable or combustible liquid in the air increases. Hence, temperature determines the concentration of vapor of the liquid in the air. The flash point is the lowest temperature at which there will be enough flammable vapor to induce ignition when a source is applied. There are two types of flash point measurement, open cup and closed cup. In open cup devices, the sample is contained in a cup which is heated and, at intervals. The measured flash point will vary with the height of the flame above the liquid surface and, at sufficient height. The best-known example is the Cleveland open cup, in both these types, the cups are sealed with a lid through which the ignition source can be introduced. Closed cup testers normally give lower values for the point than open cup and are a better approximation to the temperature at which the vapour pressure reaches the lower flammable limit. The flash point is an empirical measurement rather than a physical parameter. The measured value will vary with equipment and test protocol variations, including temperature ramp rate, time allowed for the sample to equilibrate, sample volume, methods for determining the flash point of a liquid are specified in many standards. For example, testing by the Pensky-Martens closed cup method is detailed in ASTM D93, IP34, ISO2719, DIN51758, JIS K2265 and AFNOR M07-019. Determination of flash point by the Small Scale closed cup method is detailed in ASTM D3828 and D3278, EN ISO3679 and 3680, cEN/TR15138 Guide to Flash Point Testing and ISO TR29662 Guidance for Flash Point Testing cover the key aspects of flash point testing. Gasoline is a used in a spark-ignition engine
15.
Refrigerant
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A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration cycle. In most cycles it undergoes phase transitions from a liquid to a gas, many working fluids have been used for such purposes. Fluorocarbons, especially chlorofluorocarbons, became commonplace in the 20th century, other common refrigerants used in various applications are ammonia, sulfur dioxide, and non-halogenated hydrocarbons such as propane. The ideal refrigerant would have favorable properties, be noncorrosive to mechanical components. It would not cause ozone depletion or climate change, since different fluids have the desired traits in different degree, choice is a matter of trade-off. Since boiling point and gas density are affected by pressure, refrigerants may be more suitable for a particular application by choice of operating pressures. In order from the highest to the lowest potential of ozone depletion are Bromochlorofluorocarbon, though HFC and PFC are non-ozone depleting, many have global warming potentials that are thousands of times greater than CO2. Some other refrigerants such as propane and ammonia are not inert, new refrigerants were developed in the early 21st century that are safer for the environment, but their application has been held up due to concerns over toxicity and flammability. Early mechanical refrigeration systems employed sulfur dioxide, methyl chloride and ammonia, being toxic, sulfur dioxide and methyl chloride rapidly disappeared from the market with the introduction of CFCs. Occasionally, one may encounter older machines with methyl formate, chloromethane, chlorofluorocarbons were little used for refrigeration until better synthesis methods, developed in the 1950s, reduced their cost. Their domination of the market was called into question in the 1980s by concerns about depletion of the ozone layer and they are currently subject to prohibition discussions on account of their harmful effect on the climate. In 1997, FCs and HFCs were included in the Kyoto Protocol to the Framework Convention on Climate Change, in 2006, the EU adopted a Regulation on fluorinated greenhouse gases, which makes stipulations regarding the use of FCs and HFCs with the intention of reducing their emissions. The provisions do not affect climate-neutral refrigerants, refrigerants such as ammonia, carbon dioxide and non-halogenated hydrocarbons do not deplete the ozone layer and have no or only a low global warming potential. They are used in air-conditioning systems for buildings, in sport and leisure facilities, in the industry, in the automotive industry. In these settings their toxicity is less a concern than in home equipment, emissions from automobile air conditioning are a growing concern because of their impact on climate change. From 2011 on, the European Union will phase out refrigerants with a global warming potential of more than 150 in automotive air conditioning and this will ban potent greenhouse gases such as the refrigerant HFC-134a —which has a GWP of 1410—to promote safe and energy-efficient refrigerants. One of the most promising alternatives is CO2, carbon dioxide is non-flammable, non-ozone depleting, has a global warming potential of 1. R-744 can be used as a fluid in climate control systems for cars, residential air conditioning, hot water pumps, commercial refrigeration
16.
Pentafluoroethane
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Pentafluoroethane is a refrigerant with the formula CF3CHF2. Although it has zero ozone depletion potential, it has high global warming potential, pentafluoroethane in a near zeotropic mixture with difluoromethane is known as R-410A, a common replacement for various chlorofluorocarbons in new refrigerant systems. Pentafluoroethane is also used as a fire suppression agent in fire suppression systems, HFC-125 is a gaseous fire suppression agent which can be used in clean agent fire suppression systems. The HFC-125 clean agent is stored in a container and introduced into the hazard as a gas. The agent is odorless, colorless, electrically non-conductive, non-corrosive and it is used in occupied enclosed areas that contain high-value assets. HFC-125 suppresses fire by absorbing heat energy at its molecular level faster than the heat can be generated and it also forms free radicals to chemically interfere with the chain reaction of the combustion process. This makes it an effective fire fighting agent that is safe for people. HFC-125 is a non-ozone depleting replacement for Halon 1301, in addition, HFC-125 leaves no residue on valuable equipment after discharge. HFC-125 is considered a Clean Agent and is included in the National Fire Protection Associations 2001 - Standard for Clean Agent Fire Extinguishing Systems. When introduced to the market HFC-125 was not considered safe for use in occupied spaces, the US EPA Significant New Alternative Policy listing reflected this. Generally, class B hazards require concentrations that exceed the agents no-observed-adverse-effect level so extra precautions must be taken to avoid prolonged exposure to the agent, at high temperatures, pentafluoroethane will decompose and produce hydrogen fluoride. This is observable as presence of sharp, pungent odour, which can be perceived in concentrations far below a dangerous level, other decomposition products include carbonyl fluoride, carbon monoxide and carbon dioxide. Prior to re-entry of a room where HFC-125 system has been activated to suppress a fire, an Acid Scavenging Additive added to pentafluoroethane is able to reduce the amount of hydrogen fluoride. ECARO-25 is a trademark of Fike Corporation. FE-25 is a trademark of E. I. du Pont de Nemours. NAF S125 is a trademark of Safety Hi-Tech, EPA site on hazards Commercial Site on NAF S125 Commercial Site on ECARO-25 Commercial Site on FE-25 FE-25 Safety MSDS data
17.
1-Chloro-1,2,2,2-tetrafluoroethane
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1-Chloro-1,2,2, 2-tetrafluoroethane, C2HClF4, also called R-124, is a hydrochlorofluorocarbon used as a refrigerant. The chemical is also marketed for use as a fire suppressant. Protected areas are normally unoccupied requiring an automatic fire suppression system, other clean agents are approved for occupied areas but are more expensive (see Duponts FM-200heptafluoropropane
18.
1,1,1-Trichloroethane
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The organic compound 1,1, 1-trichloroethane, also known as methyl chloroform, is a chloroalkane. This colourless, sweet-smelling liquid was once produced industrially in large quantities for use as a solvent and it is regulated by the Montreal Protocol as an ozone-depleting substance and its use is being rapidly phased out. 1,1, 1-Trichloroethane was first reported by Henri Victor Regnault in 1840, industrially, it is usually produced in a two-step process from vinyl chloride. The major side-product is the related compound 1,1, 2-trichloroethane, from which the 1,1, stabilizers comprise up to 8% of the formulation, including acid scavengers and complexants. The Montreal Protocol targeted 1,1, 1-trichloroethane as one of those responsible for ozone depletion. Since then, its manufacture and use has been phased out throughout most of the world,1,1, 1-trichloroethane is generally considered a non-polar solvent. Owing to the polarizability of the chlorine atoms, it is a superior solvent for organic compounds that do not dissolve well in hydrocarbons such as hexane. It is an excellent solvent for organic materials and also one of the least toxic of the chlorinated hydrocarbons. 1,1, 1-trichloroethane is also used as an insecticidal fumigant and it was also the standard cleaner for photographic film. Other commonly available solvents damage emulsion, and thus are not suitable for this application, the standard replacement, Forane 141 is much less effective, and tends to leave a residue. 1,1, 1-trichloroethane was used as a thinner in correction fluid products such as liquid paper, many of its applications previously used carbon tetrachloride. In turn,1,1, 1-trichloroethane itself is now being replaced by other solvents in the laboratory, fatal poisonings and illnesses linked to intentional inhalation of trichloroethane have been reported. Studies on laboratory animals have shown that 1,1, 1-trichloroethane is not retained in the body for long periods of time, however, chronic exposure has been linked to abnormalities in the liver, kidneys, and heart. Pregnant women should avoid exposure, as the compound has been linked to birth defects in laboratory animals
19.
Refractive index
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In optics, the refractive index or index of refraction n of a material is a dimensionless number that describes how light propagates through that medium. It is defined as n = c v, where c is the speed of light in vacuum, for example, the refractive index of water is 1.333, meaning that light travels 1.333 times faster in a vacuum than it does in water. The refractive index determines how light is bent, or refracted. The refractive indices also determine the amount of light that is reflected when reaching the interface, as well as the angle for total internal reflection. This implies that vacuum has a index of 1. The refractive index varies with the wavelength of light and this is called dispersion and causes the splitting of white light into its constituent colors in prisms and rainbows, and chromatic aberration in lenses. Light propagation in absorbing materials can be described using a refractive index. The imaginary part then handles the attenuation, while the real part accounts for refraction, the concept of refractive index is widely used within the full electromagnetic spectrum, from X-rays to radio waves. It can also be used with wave phenomena such as sound, in this case the speed of sound is used instead of that of light and a reference medium other than vacuum must be chosen. Thomas Young was presumably the person who first used, and invented, at the same time he changed this value of refractive power into a single number, instead of the traditional ratio of two numbers. The ratio had the disadvantage of different appearances, newton, who called it the proportion of the sines of incidence and refraction, wrote it as a ratio of two numbers, like 529 to 396. Hauksbee, who called it the ratio of refraction, wrote it as a ratio with a fixed numerator, hutton wrote it as a ratio with a fixed denominator, like 1.3358 to 1. Young did not use a symbol for the index of refraction, in the next years, others started using different symbols, n, m, and µ. For visible light most transparent media have refractive indices between 1 and 2, a few examples are given in the adjacent table. These values are measured at the yellow doublet D-line of sodium, with a wavelength of 589 nanometers, gases at atmospheric pressure have refractive indices close to 1 because of their low density. Almost all solids and liquids have refractive indices above 1.3, aerogel is a very low density solid that can be produced with refractive index in the range from 1.002 to 1.265. Moissanite lies at the end of the range with a refractive index as high as 2.65. Most plastics have refractive indices in the range from 1.3 to 1.7, for infrared light refractive indices can be considerably higher
20.
Relative permittivity
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The relative permittivity of a material is its permittivity expressed as a ratio relative to the permittivity of vacuum. Permittivity is a property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the field between the charges is decreased relative to vacuum. Likewise, relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, relative permittivity is also commonly known as dielectric constant, a term deprecated in physics and engineering as well as in chemistry. Relative permittivity is typically denoted as εr and is defined as ε r = ε ε0, where ε is the complex frequency-dependent absolute permittivity of the material, and ε0 is the vacuum permittivity. Relative permittivity is a number that is in general complex-valued, its real and imaginary parts are denoted as. The relative permittivity of a medium is related to its electric susceptibility, χe, in anisotropic media the relative permittivity is a second rank tensor. The relative permittivity of a material for a frequency of zero is known as its relative permittivity. The historical term for the relative permittivity is dielectric constant and it is still commonly used, but has been deprecated by standards organizations, because of its ambiguity, as some older authors used it for the absolute permittivity ε. The permittivity may be quoted either as a property or as a frequency-dependent variant. It has also used to refer to only the real component εr of the complex-valued relative permittivity. In the causal theory of waves, permittivity is a complex quantity, the imaginary part corresponds to a phase shift of the polarization P relative to E and leads to the attenuation of electromagnetic waves passing through the medium. By definition, the relative permittivity of vacuum is equal to 1. The relative static permittivity, εr, can be measured for static electric fields as follows, first the capacitance of a test capacitor, then, using the same capacitor and distance between its plates, the capacitance Cx with a dielectric between the plates is measured. The relative dielectric constant can be calculated as ε r = C x C0. For time-variant electromagnetic fields, this quantity becomes frequency-dependent, an indirect technique to calculate εr is conversion of radio frequency S-parameter measurement results. A description of frequently used S-parameter conversions for determination of the frequency-dependent εr of dielectrics can be found in this bibliographic source, alternatively, resonance based effects may be employed at fixed frequencies. The relative permittivity is a piece of information when designing capacitors
21.
Infrared spectroscopy
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Infrared spectroscopy involves the interaction of infrared radiation with matter. It covers a range of techniques, mostly based on absorption spectroscopy, as with all spectroscopic techniques, it can be used to identify and study chemicals. Sample may be solid, liquid, or gas, the method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer to produce an infrared spectrum. An IR spectrum is essentially a graph of infrared light absorbance on the vertical axis vs. frequency or wavelength on the horizontal axis, typical units of frequency used in IR spectra are reciprocal centimeters, with the symbol cm−1. Units of IR wavelength are commonly given in micrometers, symbol μm, a common laboratory instrument that uses this technique is a Fourier transform infrared spectrometer. Two-dimensional IR is also possible as discussed below, the infrared portion of the electromagnetic spectrum is usually divided into three regions, the near-, mid- and far- infrared, named for their relation to the visible spectrum. The higher-energy near-IR, approximately 14000–4000 cm−1 can excite overtone or harmonic vibrations, the mid-infrared, approximately 4000–400 cm−1 may be used to study the fundamental vibrations and associated rotational-vibrational structure. The far-infrared, approximately 400–10 cm−1, lying adjacent to the region, has low energy. The names and classifications of these subregions are conventions, and are loosely based on the relative molecular or electromagnetic properties. Infrared spectroscopy exploits the fact that molecules absorb frequencies that are characteristic of their structure and these absorptions occur at resonant frequencies, i. e. the frequency of the absorbed radiation matches the vibrational frequency. The energies are affected by the shape of the potential energy surfaces, the masses of the atoms. In particular, in the Born–Oppenheimer and harmonic approximations, i. e, the resonant frequencies are also related to the strength of the bond and the mass of the atoms at either end of it. Thus, the frequency of the vibrations are associated with a normal mode of motion. In order for a mode in a sample to be IR active. A permanent dipole is not necessary, as the rule requires only a change in dipole moment, a molecule can vibrate in many ways, and each way is called a vibrational mode. For molecules with N number of atoms, linear molecules have 3N –5 degrees of vibrational modes, as an example H2O, a non-linear molecule, will have 3 ×3 –6 =3 degrees of vibrational freedom, or modes. Simple diatomic molecules have only one bond and only one vibrational band, if the molecule is symmetrical, e. g. N2, the band is not observed in the IR spectrum, but only in the Raman spectrum. Asymmetrical diatomic molecules, e. g. CO, absorb in the IR spectrum, more complex molecules have many bonds, and their vibrational spectra are correspondingly more complex, i. e. big molecules have many peaks in their IR spectra
22.
Nuclear magnetic resonance spectroscopy
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Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei. This type of spectroscopy determines the physical and chemical properties of atoms or the molecules in which they are contained and it relies on the phenomenon of nuclear magnetic resonance and can provide detailed information about the structure, dynamics, reaction state, and chemical environment of molecules. Suitable samples range from small compounds analyzed with 1-dimensional proton or carbon-13 NMR spectroscopy to large proteins or nucleic acids using 3 or 4-dimensional techniques. The impact of NMR spectroscopy on the sciences has been substantial because of the range of information, NMR spectra are unique, well-resolved, analytically tractable and often highly predictable for small molecules. Thus, in organic chemistry practice, NMR analysis is used to confirm the identity of a substance, different functional groups are obviously distinguishable, and identical functional groups with differing neighboring substituents still give distinguishable signals. NMR has largely replaced traditional wet chemistry tests such as reagents or typical chromatography for identification. A disadvantage is that a large amount, 2–50 mg, of a purified substance is required. Preferably, the sample should be dissolved in a solvent, because NMR analysis of solids requires a dedicated MAS machine, the timescale of NMR is relatively long, and thus it is not suitable for observing fast phenomena, producing only an averaged spectrum. NMR spectrometers are relatively expensive, universities usually have them, modern NMR spectrometers have a very strong, large and expensive liquid helium-cooled superconducting magnet, because resolution directly depends on magnetic field strength. There are even benchtop NMR spectrometers, the Purcell group at Harvard University and the Bloch group at Stanford University independently developed NMR spectroscopy in the late 1940s and early 1950s. Edward Mills Purcell and Felix Bloch shared the 1952 Nobel Prize in Physics for their discoveries, when placed in a magnetic field, NMR active nuclei absorb electromagnetic radiation at a frequency characteristic of the isotope. The resonant frequency, energy of the absorption, and the intensity of the signal are proportional to the strength of the magnetic field, for example, in a 21 Tesla magnetic field, protons resonate at 900 MHz. It is common to refer to a 21 T magnet as a 900 MHz magnet, spinning the sample is necessary to average out diffusional motion. Whereas, measurements of diffusion constants are done the sample stationary and spinning off, the vast majority of nuclei in a solution would belong to the solvent, and most regular solvents are hydrocarbons and would contain NMR-reactive protons. The most used deuterated solvent is deuterochloroform, although deuterium oxide and deuterated DMSO are used for hydrophilic analytes, the chemical shifts are slightly different in different solvents, depending on electronic solvation effects. NMR spectra are often calibrated against the known solvent residual proton peak instead of added tetramethylsilane, to detect the very small frequency shifts due to nuclear magnetic resonance, the applied magnetic field must be constant throughout the sample volume. High resolution NMR spectrometers use shims to adjust the homogeneity of the field to parts per billion in a volume of a few cubic centimeters. In order to detect and compensate for inhomogeneity and drift in the magnetic field, in modern NMR spectrometers shimming is adjusted automatically, though in some cases the operator has to optimize the shim parameters manually to obtain the best possible resolution
23.
Mass spectrometry
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Mass spectrometry is an analytical technique that ionizes chemical species and sorts the ions based on their mass-to-charge ratio. In simpler terms, a mass spectrum measures the masses within a sample, mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a plot of the ion signal as a function of the mass-to-charge ratio, in a typical MS procedure, a sample, which may be solid, liquid, or gas, is ionized, for example by bombarding it with electrons. This may cause some of the molecules to break into charged fragments. The ions are detected by a capable of detecting charged particles. Results are displayed as spectra of the abundance of detected ions as a function of the mass-to-charge ratio. The atoms or molecules in the sample can be identified by correlating known masses to the masses or through a characteristic fragmentation pattern. Goldstein called these positively charged anode rays Kanalstrahlen, the translation of this term into English is canal rays. Wien found that the charge-to-mass ratio depended on the nature of the gas in the discharge tube, thomson later improved on the work of Wien by reducing the pressure to create the mass spectrograph. The word spectrograph had become part of the international scientific vocabulary by 1884, a mass spectroscope is similar to a mass spectrograph except that the beam of ions is directed onto a phosphor screen. A mass spectroscope configuration was used in early instruments when it was desired that the effects of adjustments be quickly observed, once the instrument was properly adjusted, a photographic plate was inserted and exposed. The term mass spectroscope continued to be used though the direct illumination of a phosphor screen was replaced by indirect measurements with an oscilloscope. The use of the mass spectroscopy is now discouraged due to the possibility of confusion with light spectroscopy. Mass spectrometry is often abbreviated as mass-spec or simply as MS, modern techniques of mass spectrometry were devised by Arthur Jeffrey Dempster and F. W. Aston in 1918 and 1919 respectively. Sector mass spectrometers known as calutrons were used for separating the isotopes of uranium developed by Ernest O. Lawrence during the Manhattan Project, calutron mass spectrometers were used for uranium enrichment at the Oak Ridge, Tennessee Y-12 plant established during World War II. In 1989, half of the Nobel Prize in Physics was awarded to Hans Dehmelt, a mass spectrometer consists of three components, an ion source, a mass analyzer, and a detector. The ionizer converts a portion of the sample into ions, there is a wide variety of ionization techniques, depending on the phase of the sample and the efficiency of various ionization mechanisms for the unknown species. An extraction system removes ions from the sample, which are then targeted through the mass analyzer, the differences in masses of the fragments allows the mass analyzer to sort the ions by their mass-to-charge ratio
24.
Haloalkane
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The haloalkanes are a group of chemical compounds derived from alkanes containing one or more halogens. They are a subset of the class of halocarbons, although the distinction is not often made. Haloalkanes are widely used commercially and, consequently, are known under many chemical and commercial names and they are used as flame retardants, fire extinguishants, refrigerants, propellants, solvents, and pharmaceuticals. Subsequent to the use in commerce, many halocarbons have also been shown to be serious pollutants. For example, the chlorofluorocarbons have been shown to lead to ozone depletion, methyl bromide is a controversial fumigant. Only haloalkanes which contain chlorine, bromine, and iodine are a threat to the ozone layer, haloalkane or alkyl halides are the compounds which have the general formula RX where R is an alkyl or substituted alkyl group and X is a halogen. Haloalkanes have been known for centuries, chloroethane was produced synthetically in the 15th century. The systematic synthesis of such compounds developed in the 19th century in step with the development of organic chemistry, methods were developed for the selective formation of C-halogen bonds. Especially versatile methods included the addition of halogens to alkenes, hydrohalogenation of alkenes, while most haloalkanes are human-produced, non-artificial-source haloalkanes do occur on Earth, mostly through enzyme-mediated synthesis by bacteria, fungi, and especially sea macroalgae. More than 1600 halogenated organics have been identified, with bromoalkanes being the most common haloalkanes, brominated organics in biology range from biologically produced methyl bromide to non-alkane aromatics and unsaturates. Halogenated alkanes in land plants are rare, but do occur. Specific dehalogenase enzymes in bacteria which remove halogens from haloalkanes, are also known, from the structural perspective, haloalkanes can be classified according to the connectivity of the carbon atom to which the halogen is attached. In primary haloalkanes, the carbon that carries the halogen atom is attached to one other alkyl group. In secondary haloalkanes, the carbon that carries the halogen atom has two C–C bonds, in tertiary haloalkanes, the carbon that carries the halogen atom has three C–C bonds. Haloalkanes can also be classified according to the type of halogen on group 7 responding to a specific halogenoalkane, haloalkanes containing carbon bonded to fluorine, chlorine, bromine, and iodine results in organofluorine, organochlorine, organobromine and organoiodine compounds, respectively. Compounds containing more than one kind of halogen are also possible, several classes of widely used haloalkanes are classified in this way chlorofluorocarbons, hydrochlorofluorocarbons and hydrofluorocarbons. These abbreviations are common in discussions of the environmental impact of haloalkanes. Haloalkanes generally resemble the parent alkanes in being colorless, relatively odorless and their boiling points are higher than the corresponding alkanes and scale with the atomic weight and number of halides
25.
Dichlorodifluoromethane
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Dichlorodifluoromethane is a colorless gas usually sold under the brand name Freon-12, and a chlorofluorocarbon halomethane used as a refrigerant and aerosol spray propellant. Complying with the Montreal Protocol, its manufacture was banned in developed countries in 1996 and its only allowed usage is as fire retardant in submarines and aircraft. It is soluble in organic solvents. Dichlorodifluoromethane was one of the propellants for Silly String. Charles Kettering, vice president of General Motors Research Corporation, was seeking a refrigerant replacement that would be colorless, odorless, tasteless, nontoxic and he assembled a team that included Thomas Midgley, Jr. Albert Leon Henne, and Robert McNary. The use of chlorofluorocarbons as aerosols in medicine, such as USP-approved salbutamol, has been phased out by the U. S. Food, a different propellant known as hydrofluoroalkane, or HFA, which is not known to harm the environment, was chosen to replace it. R-12 was used in most refrigeration and vehicle air conditioning applications prior to 1994 before being replaced by 1,1,1, 2-tetrafluoroethane, automobile manufacturers started using R-134a instead of R-12 in 1992–1994. When older units leak or require repair involving removal of the refrigerant, retrofitment to a refrigerant other than R-12 is required in some jurisdictions, mineral oil used with R-12 is not compatible with R-134a. Some oils designed for conversion to R-134a are advertised as compatible with residual R-12 mineral oil
26.
2,3,3,3-Tetrafluoropropene
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2,3,3, 3-Tetrafluoropropene, or HFO-1234yf, is a hydrofluoroolefin with the formula CH2=CFCF3. This colorless gas has been proposed as a replacement for R-134a as a refrigerant in automobile air conditioners, HFO-1234yf is the first in a new class of refrigerants acquiring a global warming potential rating one 335th that of R-134a and an atmospheric lifetime of about 400 times shorter. HFO-1234yf, which has a 100-year GWP lower than 1, could be used as a near drop-in replacement for R-134a, the current product used in automobile AC systems, which has a 100-year GWP of 1430. This means that automakers would not have to make significant modifications in assembly lines or in vehicle system designs to accommodate the product. HFO-1234yf has the lowest switching cost for automakers among the proposed alternatives. The product could be handled in repair shops in the way as R-134a, although it would require different. One of the reasons for that is the mild flammability of HFO-1234yf, another issue affecting the compatibility between HFO-1234yf and R-134a-based systems is the choice of lubricating oil. The current lubricating oil is showing signs of damage to plastic and aluminium, and issues with health, including mouth dryness, rashes, in addition, Honeywell is building a new plant in Geismar, Louisiana, USA to produce the new refrigerant as well. Although others claim to be able to make and sell HFO-1234yf, Honeywell, on July 23,2010, General Motors announced that it will introduce HFO-1234yf in 2013 Chevrolet, Buick, GMC, and Cadillac models in the U. S. Although the product is classified slightly flammable by ASHRAE, several years of testing by SAE proved that the product could not be ignited under conditions normally experienced by a vehicle. In addition several independent authorities evaluated the safety of the product in vehicles and some of them concluded that it was as safe to use as R-134a, the product in use in cars today. In the atmosphere, HFO-1234yf degrades to trifluoroacetic acid, which is a mildly phytotoxic strong organic acid with no known biodegradation mechanism in water, in case of fire it releases highly corrosive and toxic hydrogen fluoride and the highly toxic gas carbonyl fluoride. In December 2012, Mercedes-Benz showed that the substance ignited when researchers sprayed it, a senior Daimler engineer who ran the tests, stated We were frozen in shock, I am not going to deny it. We needed a day to comprehend what we had just seen, combustion occurred in more than two thirds of simulated head-on collisions. The engineers also noticed etching on the windshield caused by the corrosive gases, BMW, and VW-Audi agreed with Mercedes and left the SAE R-1234yf CRP Team, stating that the performed tests are not sufficient to fully judge the safety of their vehicles. The German automakers have been leaning towards carbon dioxide refrigerant, which may be safer for both passengers and the environment, following Mercedes claims that the new refrigerant could be ignited, Germanys Kraftfahrt-Bundesamt conducted its own tests. The Authority concluded that while the substance was more hazardous than previously used R-134a. However the German automakers disagree with their findings, and test procedures, following other independent and in house testing, General Motors still plans to transition all new models to the new refrigerant by 2018
27.
Combustibility and flammability
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Combustibility is a measure of how easily a substance will set on fire, through fire or combustion. This is an important property to consider when a substance is used for construction or is being stored and it is also important in processes that produce combustible substances as a by-product. Special precautions are required for substances that are easily combustible. These measures may include installation of fire sprinklers or storage remote from possible sources of ignition, substances with low combustibility may be selected for construction where the fire risk needs to be reduced, such as apartment buildings, houses, or offices. If combustible resources are used there is chance of fire accidents. Fire resistant substances are preferred for building materials and furnishings, for an Authority Having Jurisdiction, combustibility is defined by the local code. BS 476-4,1970 defines a test for combusibility in which 3 specimens of a material are heated in a furnace, otherwise, the material shall be deemed combustible. Various countries have tests for determining noncombustibility of materials, most involve the heating of a specified quantity of the test specimen for a set duration. Usually, the material cannot support combustion and must not undergo a loss of mass. In Canada, for instance, firewalls must be made of concrete, in building construction, buildings are typically divided into combustible and noncombustible ones. Combustible structures have more stringent limits on building height and area. A number of industrial processes produce combustible dust as a by-product, the most common being wood dust. In addition to wood, combustible dusts include metals, especially magnesium, titanium and aluminum, there are at least a 140 known substances that produce combustible dust. While the particles in a combustible dusts may be of any size, as of 2012, the United States Occupational Safety and Health Administration has yet to adopt a comprehensive set of rules on combustible dust. When suspended in air, the particles of combustible dust present a potential for explosions. Accumulated dust, even when not suspended in air, remains a fire hazard, collectors designed to reduce airborne dust account for more than 40 percent of all dust explosions. Other important processes are grinding and pulverizing, transporting powders, filing silos and containers, investigation of 200 dust explosions and fires, between 1980 to 2005, indicated approximately 100 fatalities and 600 injuries. In January 2003, a powder explosion and fire at the West Pharmaceutical Services plant in Kinston, North Carolina resulted in the deaths of six workers
28.
Refrigeration
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Refrigeration is a process of moving heat from one location to another in controlled conditions. The work of heat transport is driven by mechanical work. Refrigeration has many applications, including, but not limited to, household refrigerators, industrial freezers, cryogenics, heat pumps may use the heat output of the refrigeration process, and also may be designed to be reversible, but are otherwise similar to air conditioning units. Refrigeration has had a impact on industry, lifestyle, agriculture. The idea of preserving food dates back to at least the ancient Roman, however, mechanical refrigeration technology has rapidly evolved in the last century, from ice harvesting to temperature-controlled rail cars. Settlements were also developing in parts of the country, filled with new natural resources. These new settlement patterns sparked the building of cities which are able to thrive in areas that were otherwise thought to be inhospitable, such as Houston, Texas and Las Vegas. In most developed countries, cities are heavily dependent upon refrigeration in supermarkets, the increase in food sources has led to a larger concentration of agricultural sales coming from a smaller percentage of existing farms. Farms today have a larger output per person in comparison to the late 1800s. This has resulted in new food sources available to entire populations, the seasonal harvesting of snow and ice is an ancient practice estimated to have begun earlier than 1000 B. C. A Chinese collection of lyrics from this period known as the Shih king. However, little is known about the construction of these ice cellars or what the ice was used for. ”Historians have interpreted this to mean that the Jews used ice to cool beverages rather than to preserve food. Other ancient cultures such as the Greeks and the Romans dug large snow pits insulated with grass, chaff, like the Jews, the Greeks and Romans did not use ice and snow to preserve food, but primarily as a means to cool beverages. Slaves would moisten the outside of the jars and the resulting evaporation would cool the water, the ancient people of India used this same concept to produce ice. The Persians stored ice in a pit called a Yakhchal and may have been the first group of people to use storage to preserve food. In the Australian outback before a reliable electricity supply was available where the weather could be hot and dry and this consisted of a room with hessian curtains hanging from the ceiling soaked in water. The water would evaporate and thereby cool the hessian curtains and thereby the air circulating in the room and this would allow many perishables such as fruit, butter, and cured meats to be kept that would normally spoil in the heat. Before 1830, few Americans used ice to refrigerate foods due to a lack of ice-storehouses and iceboxes, as these two things became more widely available, individuals used axes and saws to harvest ice for their storehouses
29.
Automobile air conditioning
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Automobile air conditioning systems use air conditioning to cool the air in a vehicle. A company in New York City in the United States first offered installation of air conditioning for cars in 1933, most of their customers operated limousines and luxury cars. In 1939, Packard became the first automobile manufacturer to offer an air conditioning unit in its cars and these were manufactured by Bishop and Babcock Co, of Cleveland, Ohio. The Bishop and Babcock Weather Conditioner also incorporated a heater, cars ordered with the new Weather Conditioner were shipped from Packards East Grand Boulevard facility to the B&B factory where the conversion was performed. Once complete, the car was shipped to a local dealer where the customer would take delivery, Packard fully warranted and supported this conversion, and marketed it well. However, it was not commercially successful for a number of reasons, The main evaporator and it was superseded by more efficient systems in the post-war years. It had no temperature thermostat or shut-off mechanism other than switching the blower off, the several feet of plumbing going back and forth between the engine compartment and trunk proved unreliable in service. The price, at US $274, was unaffordable to most people in post-depression/pre-war America, the option was discontinued after 1941. Walter Chrysler had seen to the invention of Airtemp air conditioning in the 1930s for the Chrysler Building, and had offered it on cars in 1941-42, the Airtemp was more advanced than rival automobile air conditioners by 1953. It was operated by a switch on the dashboard marked with low, medium. As the highest capacity unit available at time, the system was capable of quickly cooling the passenger compartment and also reducing humidity, dust, pollen. The system drew in more air than contemporary systems, thus. Cadillac, Buick, and Oldsmobile added air conditioning as an option on some of their models in the 1953 model year, all of these Frigidaire systems used separate engine and trunk mounted components. In 1954, the Nash Ambassador was the first American automobile to have a front-end, fully integrated heating, ventilating and this was the first mass market system with controls on the dash and an electric clutch. This system was also compact and serviceable with all of its components installed under the hood or in the cowl area, combining heating, cooling, and ventilating, the new air conditioning system for the Nash cars was called the All-Weather Eye. This followed the name of Weather Eye for Nashs fresh-air automotive heating and ventilating system that was first used in 1938. With a single control, the Nash passenger compartment air cooling option was a good. The system had cold air for passengers enter through dash-mounted vents, Nashs exclusive remarkable advance was not only the sophisticated unified system, but also its $345 price that beat all other systems
30.
Bronchodilator
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Bronchodilator, A bronchodilator is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lungs. Bronchodilators may be endogenous, or they may be administered for the treatment of breathing difficulties. They are most useful in obstructive lung diseases, of which asthma, although this remains somewhat controversial, they might be useful in bronchiolitis and Bronchiectasis. They are often prescribed but of significance in restrictive lung diseases. Bronchodilators are either short-acting or long-acting, short-acting medications provide quick or rescue relief from acute bronchoconstriction. Long-acting bronchodilators help to control and prevent symptoms, the three types of prescription bronchodilating drugs are β2-agonists, anticholinergics, and theophylline. These are quick-relief or rescue medications that provide quick, temporary relief from asthma symptoms or flare-ups and these medications usually take effect within 20 minutes or less, and can last from four to six hours. These inhaled medications are best for treating sudden and severe or new asthma symptoms, taken 15 to 20 minutes ahead of time, these medications can also prevent asthma symptoms triggered by exercise or exposure to cold air. Some short-acting β-agonists are specific to the lungs, they are called β2-agonists, patients who regularly or frequently need to take short-acting β-agonists should consult their doctor, as such usage indicates uncontrolled asthma, and their routine medications may need adjustment. These are long-term medications taken routinely in order to control and prevent bronchoconstriction and they are not intended for fast relief. These medications may take longer to begin working, but relieve airway constriction for up to 12 hours, commonly taken twice a day with an anti-inflammatory medication, they maintain open airways and prevent asthma symptoms, particularly at night. Salmeterol and formoterol are examples of these, some examples of anticholinergics are tiotropium and ipratropium bromide. Tiotropium is a long-acting, 24-hour, anticholinergic bronchodilator used in the management of chronic pulmonary disease. Only available as an inhalant, ipratropium bromide is used in the treatment of asthma and it relieves acute or new asthma symptoms. It will not stop an asthma attack already in progress, because it has no effect on asthma symptoms when used alone, it is most often paired with a short-acting β2-agonist. While it is considered a relief or rescue medication, it can take an hour to begin working. For this reason, it plays a role in asthma treatment. Dry throat is the most common side effect, if the medication gets in contact with the eyes, it may cause blurred vision for a brief time
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Gas duster
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Gas duster, also known as canned air or compressed air, is a product used for cleaning or dusting electronic equipment and other sensitive devices that cannot be cleaned using water. The products are most often a can that, when a trigger is pressed, despite the name canned air, the cans actually contain gases that are compressable into liquids. Air on the contrary, cannot be compressed into liquid at any pressure since the temperatures of air components are much beyond normal handling temperatures. Duster gases are such as 1, 1-difluoroethane,1,1, 1-trifluoroethane, hydrocarbons, like butane, were often used in the past, but their flammable nature forced manufacturers to use fluorocarbons. When inhaled, gas duster fumes may produce psychoactive effects and may be harmful to health, since gas dusters are one of the many inhalants that can be easily abused, many manufacturers have added a bittering agent to deter people from inhaling the product. Because of the name canned air, it was mistakenly believed that the can only contains normal air or contains a less harmful substance such as nitrous oxide. However, the actually used are denser than air, such as difluoroethane. When inhaled, the gas displaces the oxygen in the lungs and this type of inhalant abuse can cause a plethora of negative effects including brain and nerve damage, paralysis, serious injury, or death. The liquid, when released from the can, boils at a low temperature. This can cause mild to moderate frostbite on contact with skin, also, the can gets very cold during extended use, holding the can itself can result in cold burns. Since gas dusters are often contained in vessels, they are considered explosively volatile. Global warming, Difluoroethane, trifluoroethane, and completely non-flammable tetrafluoroethane are potent greenhouse gases, according to the Intergovernmental Panel on Climate Change, the global warming potential of HFC-152a, HFC-143a, and HFC-134a are 124,4470, and 1430, respectively. GWP refers to global warming effect in comparison to CO2 for unit mass and this is a separate issue from the global warming concern. Many gas dusters contain HFC-134a, which is used as a propellant and refrigerant. HFC-134a sold for those purposes is often sold at a higher unit price. Adapters have been built for such purposes, though in most cases, one example of this practice is the case of airsoft gas guns, which use HFC-134a as the compressed gas. Several vendors sell duster adapters for use with airsoft guns, though it is necessary to add a lubricant when using gas dusters to power airsoft guns, true air dusters using ordinary air are also available in the market. These typically have much shorter run times than a chemical duster, both hand pump and electric compressor models have been marketed
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. PMID 25937660. 
