...of 33 chemical elements, grouping them into gases, metals,nonmetals, and earths.[42] Chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together in a triad as soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third;[43]this became known as the Law of Triads.[44] German chemist Leopold Gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. Jean-Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all.[43] In 1858, German chemist August Kekulé observed that carbon often has four other atoms bonded to it.Methane, for example, has one carbon atom and four hydrogen atoms. This concept eventually became known as valency; different elements bond with different numbers of atoms.[45] In 1862, Alexandre-Emile Béguyer de Chancourtois, a French geologist, published an early form of periodic table, which he called the telluric helix or screw. He was the first person to notice the periodicity of the...
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...Lavoisier published a list of 33 chemical elements, grouping them into gases, metals, nonmetals, and earths. Chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together in a triad as soft. German chemist Leopold Gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. Jean-Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all. In 1858, German chemist August Kekulé observed that carbon often has four other atoms bonded to it. Methane, for example, has one carbon atom and four hydrogen atoms. This concept eventually became known as valency; different elements bond with different numbers of atoms. In 1864, fellow German chemist Julius Lothar Meyer published a table with 44 elements arranged by valency. The table showed that elements with similar properties often shared the same valency. English chemist John Newlands produced a series of papers in 1864 and 1865 noting that when the elements were listed in order of increasing atomic weight, similar physical and chemical properties recurred at intervals...
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...these have different properties. Different atoms can also combine to form molecules. Hydrogen combines with sulfur to form H2S and hydrogen and oxygen also combine to form H2O. Dmitri Mendeleev’s Periodic table is based on atomic weight, whereas, the modern periodic table keeps the atomic number as the base. An atomic table arranges elements from left to right in a row with the atomic number and properties gradually changing. The elements on the next row will actually exhibit similar properties as the ones above or below it. This provides an example of the periodicity nature of the elements. The columns of different elements in a period have the same or very similar properties. The properties of the elements change gradually as the columns move down through the periodic table. Atoms in similar families, such as H2S and H2O, exhibit both similar properties and molecular structure. This shows periodicity in both the molecules and the individual atoms. Alkali metals contain a single electron in their outer shell rendering them highly reactive. This allows them to be ready to donate this single electron to form molecules with substances like water. Halogens are also extremely reactive containing seven electrons in their outer shell. Similar to alkali metals, halogens need only one electron in their outer shell to become stable. The reactivity of an element increases the when the number of outer shell electrons is closer to one or seven. Elements that contain eight...
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...Through the years, the AFP Intelligence Community (AFPIC) has strived to become a highly capable, dynamic and unified military institution committed to excellence in providing timely, accurate and relevant intelligence at all levels of Command for the accomplishment of the AFP Mission. In pursuit of this goal, the AFPIC recognizes the need to gain the trust and support of our people, for Intelligence is in itself ‘about people and the study of people’. It is imperative for them to know that military intelligence personnel, in the performance of their inherent tasks, are governed by rules and procedures that would ensure the protection of human rights and civil liberties. The Office of the Deputy Chief of Staff for Intelligence J2 is publishing this “Human Rights-Based Intelligence Operations Guidebook (Rules of Behavior for Military Intelligence Personnel)” with this objective in mind, to broaden the public’s understanding of our mission and challenges, and to help us become better and stronger partners committed to serve and defend our country. Designed to further harmonize all intelligence operations with the principles of human rights and International Humanitarian Law (IHL), this Guidebook is one of the contributions of the AFPIC to the Internal Peace and Security Plan (IPSP) “Bayanihan” of the AFP and to the Security Sector Reform Agenda of the Commanderin-Chief, President Benigno S Aquino III. The essential characteristics of this Guidebook...
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...properties of elements and their compounds was acquired by chemists (a 1790 article on the elements). By 1869, a total of 63 elements had been discovered. As the number of known elements grew, scientists began to recognize patterns in properties and began to develop classification schemes. Law of Triads In 1817 Johann Dobereiner noticed that the atomic weight of strontium fell midway between the weights of calcium and barium, elements possessing similar chemical properties. In 1829, after discovering the halogen triad composed of chlorine, bromine, and iodine and the alkali metal triad of lithium, sodium and potassium he proposed that nature contained triads of elements the middle element had properties that were an average of the other two members when ordered by the atomic weight (the Law of Triads). This new idea of triads became a popular area of study. Between 1829 and 1858 a number of scientists (Jean Baptiste Dumas, Leopold Gmelin, Ernst Lenssen, Max von Pettenkofer, and J.P. Cooke) found that these types of chemical relationships extended beyond the triad. During this time fluorine was added to the halogen group; oxygen, sulfur,selenium and tellurium were grouped into a family while nitrogen, phosphorus, arsenic, antimony, and bismuth were classified as another. Unfortunately, research in this area was hampered...
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...everything around us are composed of atoms rather we can see them or not. Some elements are bonded with a variety of atoms to help form the molecules. All matter is made up of atoms that are very small, so small that they human eye cannot see. It does not matter if the liquid, solid, or gas even if it is a mixture or pure. These basic elements are the same elements that make up what is known as the periodic table. Mendeleev Demetri Mendeleev created the periodic table and was trying to put the elements in order by the weight that he saw. As the weights grew from time to time the attributes of one element may be similar to those Mendeleev listed. So Mendeleev would put the elements in a column that were alike chemically (Tro, 2009). All chemicals in the vertical rows of the periodic table were considered to be family because the attributes were a lot alike. In group 1A of the table of elements are the alkali metals, in column 7A are the halogens (Tro, 2009). Noble gases are in the column of 8A, the noble gases are in this specific column because they are gases that are unreactive because the shell has being closed. So because of similarities Mendeleev built has table of elements based on similarities. Atoms Atoms are considered the smallest existence that has similar attributes of an element, but the atom cannot be broken down into a smaller part. The formation of molecules happens when two or more atoms are put together, which can happen in many different ways. When two atoms...
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...------------------------------------------------- Histor First systemization attempts In 1789, Antoine Lavoisier published a list of 33 chemical elements, grouping them into gases, metals, nonmetals, and earths; Chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties.Lithium, sodium, and potassium, for example, were grouped together in a triad as soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third; this became known as the Law of Triads. German chemist Leopold Gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. Jean-Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all. In 1858, German chemist August Kekulé observed that carbon often has four other atoms bonded to it. Methane, for example, has one carbon atom and four hydrogen atoms. This concept eventually became known as valency; different elements bond with different numbers of atoms. In 1864, fellow German chemist Julius Lothar Meyer published a table of the 49 known elements arranged...
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...CHEMISTRY CHEMISTRY (CLASSES XI–XII) Rationale Higher Secondary Stage is the most crucial stage of school education because at this stage specialised discipline based, content oriented courses are introduced. Students reach this stage after 10 years of general education and opt for Chemistry with a purpose of mostly for pursuing their career in basic sciences or professional courses like medicines, engineering, technology and studying courses in applied areas of science and technology at tertiary level. Therefore, at this stage, there is a need to provide learners with sufficient conceptual background of Chemistry, which will make them competent to meet the challenges of academic and professional courses after the higher secondary stage. National Curriculum Framework for School Education – 2005 recommends a disciplinary approach with appropriate rigour and depth with the care that syllabus is not heavy and at the same time it is comparable to the international level. It emphasizes a coherent focus on important ideas within the discipline that are properly sequenced to optimize learning. It recommends that theoretical component of Higher Secondary Science should emphasize on problem solving methods and the awareness of Syllabus for Secondary and Higher Secondary Levels 22 historical development of key concepts of science be judiciously integrated into content. The present exercise of syllabus development in Chemistry at Higher Secondary Stage is based on this framework...
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...Chem Notes Unit 1: Quantitative Chemistry, Measurement and Data Processing Unit Conversions: dm3 (decimeter^3) = L (liters) cm3 (centimeter^3) = mL (milliliters) 0 ° C (degrees celsius) = 273.15 K (Kelvin) convert Celsius into Kelvin by adding 273.15 to the current value The difference between Accuracy and Precision: Accuracy → difference between average of measured values and true value Precision → the reproducibility of the measurements, how close they are to eachother Types of Error: Systematic Error → fundamental flaws in equipment, observer. Leads to values all higher or lower than actual value. High precision, low accuracy. Random Error → uncertainty in measurement devices. Leads to random variation in values. Always occurs and can generally not be improved. Precise measurements have low random error. Accurate measurements have low systematic error and generally low random error. Uncertainties: Graduated/Analog Device → ±1/2 of the smallest increment on the device. Digital Device → ±1 on the last digit the device records (it estimates for you.) Exact Values → No uncertainty. For all uncertainties the recorded value MUST be to the same decimal place as the uncertainty. Change your final answer's significant digits if necessary. Uncertainties should be rounded to ONE digit. Propagation of Uncertainties: Addition and Subtraction → Add uncertainties. Multiplication and Division → Calculate Relative Uncertainty by dividing...
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...CARIBBEAN EXAMINATIONS COUNCIL Caribbean Secondary Education Certificate CSEC® CHEMISTRY SYLLABUS Effective for examinations from May–June 2015 CXC 21/G/SYLL 13 Published by the Caribbean Examinations Council. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means electronic, photocopying, recording or otherwise without prior permission of the author or publisher. Correspondence related to the syllabus should be addressed to: The Pro-Registrar Caribbean Examinations Council Caenwood Centre 37 Arnold Road, Kingston 5, Jamaica Telephone Number: + 1 (876) 630-5200 Facsimile Number: + 1 (876) 967-4972 E-mail Address: cxcwzo@cxc.org Website: www.cxc.org Copyright © 2013 by Caribbean Examinations Council The Garrison, St Michael BB14038, Barbados CXC 21/G/SYLL 13 Contents RATIONALE ................................................................................................................................... AIMS ............................................................................................................................................. CANDIDATE POPULATION ............................................................................................................. SUGGESTED TIME-TABLE ALLOCATION ........................................................................................ ORGANISATION OF THE SYLLABUS .................................................
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...GRAIN BASED DISTILLERY OPERATION : 86 KLPD WATER BALANCE ALL FIGURES IN METRIC TONNES (MT) INPUTS PROCESS WATER IN LIQN BOILER FEED WATER DM WATER for DISTILLATION SOFT WATER for COOLING TOWER DM WATER BLENDING RW for BOTTLE WASHING SOFT WATER DISTILLATION SOFT WATER PUMPS SEALING FERMENTER WASHING FLOOR WASHING DOMESTIC CONSUMPTION OUTPUTS 473 533 659 774 50 65 129 129 22 20 5 MT MT MT MT MT MT MT MT MT MT 2860 RECYLCE STREAMS STEAM CONDENSATE THIN SLOPS R/E to DISTILLATION PR LEES TO FERMETATION STEAM CONDENSATE SPENT LEES PR SPENT LEES RECTIFER SPENT WASH (GRAIN SLOPS) WATER IN PRODUCT CASES WATER IN BY PRODUCT BOTTLE WASHING CT EVAPORATION & DRIFT LOSSES PUMP SEALING PROCESS CONDENSATE MT BOILER BLOWDOWN DM & SOFT WATER REGENERATION MT 420 112 659 137 MT MT MT MT 50 155 65 774 129 322 16 22 2860 MT MT MT MT MT MT MT MT MT ` 420 137 573 22 BOTTLE WAHING PUMP SEALING Total Recycling /Re-utilisations of water per day 50 129 1331 MT MT MT MT MT MT MT MT TOTAL FRESH WATER INPUT 1163 WASTE STREAMS FOR TREATMENT PROCESS CONDENSATE 322 COOLING TOWER BLOWDOWN 93 BOILER BLOW DOWN 16 DM & SOFT WATER REGENERATION 22 FLOOR WASHING 20 BOTTLE WASHING 15 PRC LEES 69 TOTAL WASTE STREAMS FOR TREATMENT 488 REUSE WASTE STREAMS AFTER TREATMENT 366 WATER FOR GREEN BELT 122 MT MT MT MT MT MT MT MT MT NOTE : FIGURES GIVEN ABOVE ARE ONLY INDICATIVE AND SHALL VARY BASED ON GRAIN CHARACTERISTICS AND OVERALL PLANT OPERATING PARAMETERS...
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...CHEMICAL EQUILIBRIUM Equilibrium occurs when the rate of the forward reaction is equal to the rate of reverse reaction. Concentration of the reactants and the products remain the same. Dynamic equilibrium occurs when the processes do not stop and forward and reverse reactions still continue in both directions at the same rate. A homogeneous reaction is a reaction wherein all the reactants and products are in the same phase e.g. all are gases. A heterogeneous reaction is a reaction wherein all the reactants and products are not in the same phase. If there is no interaction between the system and its surroundings, i.e., a system from which no substances in the reaction can escape, we say it is a closed system. Calculation of the substance amount and concentration at equilibrium We can determine the concentration of the substance by dividing the number of mol of the substance at that stage of the reaction by the volume of the container in dm3, i.e.: c= n/V where c or [ ] = concentration of the substance in mol.dm-3 n = number of mol of the substance V = volume of the container in dm3 It is handy to use a table to determine these values. Example 1 A mixture of 5 mol H2(g) and 6 mol I2(g) are placed in a sealed container of 2 dm3 at a temperature of 4580C. The balanced chemical equation for the reaction is: Equilibrium is reached after a certain time. At equilibrium there is 4mol HI(g) in the container. Calculate the concentrations...
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...------------------------------------------------- Abstract The atoms in a compound are held together by a chemical bond. There are two types of chemical bond: ionic and covalent bond. An ionic or electrovalent bond results from the electrostatic attraction between metal and non-metal atoms by the transfer of electrons. _____________________________________________________________________________________ Introduction The atoms in a compound are held together by a chemical bond. There are two types of chemical bond: ionic and covalent bond. An ionic or electrovalent bond results from the electrostatic attraction between metal and non-metal atoms by the transfer of electrons. One example is the formation of bond between a sodium metal atom and a chlorine non-metal atom [1]. In contrast, covalent bond involves the sharing of valence electrons between non-metal atoms. A covalent bond becomes polar when there is unequal sharing of bonding electrons. This happens when the elements involved in the bond has a significant difference in their electronegativity, such as in hydrochloric acid, HCl. Equal distribution of bonding electrons leads to the formation of a non-polar covalent bond. This happens when there is small or no difference in electronegativity between the atoms in a bond. Chlorine gas, Cl2, has a non-polar covalent bond. Electrical conductivity, the flow of electric current, can be used as a basis for determining the type of chemical bond present in a compound. An ionic compound, when dissolved in an...
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...The difference between a mixture and a compound is that a mixture is a substance made by mixing other substances together. Most of the time two or more substances that are chemically united and they do not exist in fixed proportions of each other. Unlike a compound a mixture can be physically separated into pure compounds or elements. For example a cake is made up of different substances that are mixed together that are separated. A compound on the other hand is just the opposite of a mixture. A compound has a constant composition with fixed ratio of elements. It can have properties different from its constituents as a new substance is formed when they are chemically combined. The difference is that a compound can only be separated by chemical methods. That is like taking platinum and gold and melting them both down together. You get platinum gold which is a mixture of two elements combined together. 2. Suppose that you have a pure substance. How can you tell whether it is a compound or an element? You can tell the difference because a compound is a mixture of two or more elements. An element on the other hand is a single thing. It is actually divided into pure substances and mixtures. When we have two or more things that are not chemically combined that is called a mixture. They can be divided into homogeneous, like the particles that are throughout milk or heterogeneous, in which we can tell it is mixed like sand and salt. A pure substance on the other hand is when...
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...heard about a company named BASF before, I was worried about writing a research paper about it. However, when I visited its website, my worries disappeared, because the website had lots of valuable information that informs me about what they did in the past and what they plan to do in the future. The BASF is a chemical company that was established in 1865 in Germany. The company name, BASF, stands for Badische Anilin- und Soda-Fabrik (Baden Aniline and Soda Factory). The company has more than 140 years of history and has gone through dramatic changes, which has lead to it becoming a universal modern company. According to its website, there are more than 110,000 employees and 385 production sites all over the world, and its goal is to be a “world’s leading chemical company.” The BASF produces various chemical related products, and these are six main product categories: chemicals, plastics, performance products, functional solutions, agricultural solutions and oil & gas. A few of its competitors are Bayer AG, Dow Chemical and TOTAL. Those companies have similar business products as BASF; however, BASF seems to be the only company that does everything, from chemical related to products to oil & gas. Therefore, the BASF is pretty competitive. By doing some research about this company, I was able to find many attractions that would make students want to work for the company. First, it is a world-wide company that one can work in different regions including Europe, North America...
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