Chemical substances

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  • Chemical substances (also called pure substances) may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[2] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[3] The chemical substance index published by CAS also includes several alloys of uncertain composition.

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  • Risk assessment of chemical substances is an ever-developing discipline. Transparent and accurate risk assessments are necessary for decision-makers to make wise risk management decisions. The outcome of risk assessments may have enormous economical consequences, in addition to the consequences for human health and the environment. Globalization is a fact, with huge possibilities for economic and social prosperity. Food and consumer products are produced in one part of the world and put on the market in another....

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  • Tham khảo sách 'project gutenberg's on the antiquity of the chemical art, by james mactear', khoa học tự nhiên, hoá học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

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  • Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride) and refined sugar (sucrose). However, simple or seemingly pure substances found in nature can in fact be mixtures of chemical substances.

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  • The first edition of Toxicological Chemistry (1989) was written to bridge the gap between toxicology and chemistry. It defined toxicological chemistry as the science that deals with the chemical nature and reactions of toxic substances, their origins and uses, and the chemical aspects of their exposure, transformation, and elimination by biological systems. It emphasized the chemical formulas, structures, and reactions of toxic substances. The second edition of Toxicological Chemistry (1992) was significantly enlarged and increased in scope compared to the first edition.

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  • While the term chemical substance is a precise technical term that is synonymous with "chemical" for professional chemists, the meaning of the word chemical varies for non-chemists within the English speaking world or those using English. For industries, government and society in general in some countries,[10] the word chemical includes a wider class of substances that contain many mixtures of such chemical substances, often finding application in many vocations.

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  • Chemical substances have become an essential part of human activities. Proper use of chemical substances help human society protect itself from hunger, thirst, famine, disease, and infection with good grains, fruits, and vegetables. Synthesis, formulations, and proper use of newer drugs and pharmaceuticals have offered the benefits of improved health care to society.

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  • There are many contents in this book: physical properties of pure substances, vapor pressures of pure substances, vapor pressures of solutions, physical and chemical data, water-vapor content of gases, densities of pure substances, densities of aqueous inorganic solutions at 1 atm, densities of aqueous organic solutions, densities of miscellaneous materials, physical and chemical data, specific heats of miscellaneous materials, properties of formation and, combustion reactions.

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  • An element is a chemical substance that is made up of a particular kind of atoms and hence cannot be broken down or transformed by a chemical reaction into a different element, though it can be transmutated into another element through a nuclear reaction. This is so, because all of the atoms in a sample of an element have the same number of protons, though they may be different isotopes, with differing numbers of neutrons.

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  • Project Gutenberg Etext of An Introduction to Chemical Science by R.P. Williams Copyright laws are changing all over the world, be sure to check the laws for your country before redistributing these files!!! Please take a look at the important information in this header. We encourage you to keep this file on your own disk, keeping an electronic path open for the next readers. Please do not remove this. This should be the first thing seen when anyone opens the book. Do not change or edit it without written permission....

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  • The Project Gutenberg EBook of Experiments upon magnesia alba, Quicklime, and some other Alcaline Substances, by Joseph Black This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.net Title: Experiments upon magnesia alba, Quicklime, and some other Alcaline Substances Author: Joseph Black Release Date: February 13, 2008 ...

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  • Outside of Chicago’s City Hall is a giant Picasso sculpture of a weeping woman. For the more artistically challenged, it takes quite a while before you can “see” it, before you can really make out what Picasso was getting at and how he got there. Five miles to the south of City Hall, in the basement of the University of Chicago’s Chemistry Department, lies a piece of glassware of which the great artist would have been proud. Again to the uninitiated, it takes quite a while to “see” it. It looks like a deranged spider; indeed, those who work with it call it the Tarantula.

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  • This study was conducted within RAND’s Public Safety and Justice program. RAND Public Safety and Justice conducts research and analysis that helps inform policymakers and communities in the areas of public safety, including law enforcement, terrorism preparedness, immigration, emergency response and management, and natural disasters; criminal justice, including sentencing and corrections policy, firearms, and community violence; and drug policy, which focuses on problems related to illegal drugs and substance abuse....

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  • Human activities have a large and important impact on the environment. Naturally occurring elements or compounds are often concentrated and redistributed in the environment through industrial processes, power production, and consumer activity. For example, lead, which is found in naturally occurring mineral deposits, has become a major pollutant through its use in batteries, paints, and gasoline additives.

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  • Through the studies, we can deduce that most of the industrial discharge carries toxic substances. Due to the presence of high amount of toxic, carcinogen, and teratogen of metals, researchers are highly concerned with its effect on the environment and health of mankind. Rigorous investigations are currently being carried out to study the consequences of the contamination on the surface water, groundwater, and surface land due to industrial discharge.

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  • Introduction: The chemical warfare agents well known count only about 30 kinds of compounds, such as sarin, soman, tabun, VX, mustard gas, lewisite and others. When unknown toxic substances should be analyzed upon the occurrence of chemical terrorism, much more kinds of poisons and related compounds become the objects of analysis. In the Chemical Weapons Convention (CWC)a, 120 thousand compoundsb, including typical chemical warfare agents, their related compounds, precursors and decomposition products, are being listed to be controlled.

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  • The Project Gutenberg EBook of The Handbook of Soap Manufacture, by W. H. Simmons and H. A. Appleton This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.net Title: The Handbook of Soap Manufacture Author: W. H. Simmons H. A. Appleton Release Date: June 7, 2007

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  • The Physical Chemistry In Brief offers a digest of all major formulas, terms and definitions needed for an understanding of the subject. They are illustrated by schematic figures, simple worked-out examples, and a short accompanying text. The concept of the book makes it different from common university or physical chemistry textbooks. In terms of contents, the Physical Chemistry In Brief embraces the fundamental course in physical chemistry as taught at the Institute of Chemical Technology, Prague, i.e.

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  • The Project Gutenberg EBook of An Elementary Study of Chemistry, by William McPherson and William Edwards Henderson This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org Title: An Elementary Study of Chemistry Author: William McPherson William Edwards Henderson Release Date: March 18, 2007

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  • Reactive liquid-liquid extraction of inorganic acids with amines and effect of solvating diluents; Liquid extraction of tall oil from wastewaters of paper industry • Supercritical fluid extraction of natural products; Enzymatic reactions in supercritical CO2; Solubilities of liquids and solids in dense CO2 with entrainer • Relation between the morphology and application properties of polymer catalysts and adsorbents • Study of the permeation and pervaporation of volatile organic substance (propan-1-ol, toluene) • Observation of the competitive adsorption on Vycor glass membr...

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