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
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Contents PART XV ANALYTICAL CHEMISTRY Chapter 63 Detecting the presence of chemical species Action of heating solid sample strongly 1 Chapter 64 Separation and purification methods Centrifugation Sublimation Partition equilibrium of a solute between two immiscible solvents Two-dimensional thin-layer chromatography 2 2 3 6 Chapter 65 Quantitative methods of analysis Detection of end point in acid-alkali titration 8 Chapter 66 Instrumental analytical methods More
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Essay ozone depletion is a serious problem presently facing the world. The ozone layer protects humans‚ animals‚ and plants from harmful ultraviolet rays. Money and time are being spent on ozone repair‚ but the problem still exists. The ozone layer is a region of the stratosphere containing ozone‚ or O3 gas. The ozone layer is necessary to both plant and animal life on earth because it protects the surface from dangerous ultraviolet light. However‚ manufacturing and household chemicals
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Agency and Atmosphere Model (CMAM)‚ partners in the universities and developed jointly by scientists industry to collect data about reac- from Environment Canada and the tive nitrogen compounds‚ chlorine universities‚ provides a sophistiand bromine compounds‚ ozone‚ cated representation of important aerosols‚ and other substances that physical and chemical processes play a critical role in the chemin the upper troposphere and the istry of the upper troposphere and stratosphere.The model
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Global Warming Problem Solving Theory BY 6/30/2014 OUTLINE 1. Introduction …………………………………………………………….3 2. Global Warming .....…………………………………………………………3 3. Conclusion ……………………………………………………………
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In the first part of this experiment acetic anhydride was used to prepare acetanilide which could then be readily brominated to form a mono-brominated product‚ with the bromine positioned at either the ortho‚ meta or para position on the aromatic ring. Acetic anhydride is very reactive towards nucleophiles and this reactivity is the result of the difference in electronegativities of the carbon and oxygen atoms that are bonded in acetic anhydride. This difference in electronegativities causes one
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urease‚ gelatin hydrolysis‚ lysine decarboxylase‚ and tryptophan deaminase. In assimilation tests using API 20 NE among 12 carbon sources tested‚ growth of strain N-5 was observed only in the presence of glucose‚ maltose‚ and malate (Table 1). In addition‚ biochemical identification and metabolic characterization of strain N-5 were performed using the Biolog identification system.35 Since strain N-5 was found to be a Gram-negative and oxidase positive‚ GN2 microplate was used. Table S1 shows a summary
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Abstract: The purpose of this lab was to synthesize triphenylmethanol from benzophenone and bromobenzene by the formation of a Grignard compound with the reagents bromobenzene and magnesium metal. The bromobenzene was first transformed into the Grignard compound and was then reacted with the benzophenone to make the final product. The mixture was then mixed with sulfuric acid and the organic layer was extracted via a separatory funnel. The mixture was then recrystallized from methanol and was allowed
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OCR gateway Core C1 revision notes Anything written in purple is for higher tier Exam tips are in red Fossil Fuels 3 types Coal (made from dead plants that lived millions of years ago) Crude oil (made from dead sea creatures that lived millions of years ago) Natural gas (made from dead sea creatures that lived millions of years ago) Key words to learn Non-renewable- fossil fuels are said to be this as we are using them up faster than they can be made Finite- these will run out if we
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recrystallized from methanol‚ yielding 0.128g of pale yellow crystals with a melting point of 131-135 oC. This represents 0.33% of the original mass of the two yolks. The cholesterol was then dissolved in ether and further purified by bromination with a bromine/acetic acid reagent and debromination with zinc powder‚ a series of aqueous washes‚ and a final recrystallization from methanol. Here‚ a yield of 28% was recovered from an initial mass of 100 mg of recrystallized material. The melting point of the
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