Factors Affecting the Band Gap of LEDs By Mohammad Reza Farham Chemistry 222 Thursday 08.02.2012
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NH3 H2O - NH4OH can be a very useful to the society because by keeping an eye out for this synthesis reaction‚ chemical technicians are able to identify ammonium hydroxide in water accessed by people and prevent people from being in contact with toxic water. Ammonia takes the form of gas at room temperature. It is a colourless gas with an irritating odour. Ammonias melting point is at -77 degrees Celsius and its boiling point is at -33.35 degrees Celsius. This covalent compound is corrosive to
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evaporator‚ absorber‚ condenser and pump of vapour absorption system for a capacity of 0.25TR and experimentally developed and run system to validated for reducing the temperature for the free of cost of operation. Keywords: Absorption‚ absorber‚ NH3‚ VAR‚ VCR. I. INTRODUCTION In the vapour absorption refrigeration (VAR) system‚ a physicochemical process replaces the mechanical pro-cess of the vapour compression refrigeration (VCR) sys-tem by using energy in the form of heat rather than mechanical
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responsible for the colour of a transition metal complex? A. B. C. D. The absorption of light when electrons move between s orbitals and d orbitals The emission of light when electrons move between s orbitals and d orbitals The absorption of light when electrons move between different d orbitals The emission of light when electrons move between different d orbitals 8809-6101 Turn
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Analytical chemistry Analytical chemistry is the branch of chemistry that deals with the separation‚ identification and determination of components in a sample. Analytical chemistry can be divided into two branches‚ qualitative and quantitative. Qualitative analysis It deals with the identity of the constituents that are in an analytical sample. Quantitative analysis It deals with the determination of how much of a given substance is in the sample. The quantitative analyses are classified
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arise in one of two forms: conjugated pi systems (also known as resonating systems) and metal complexes. [edit]Conjugated pi-bond system chromophores In the conjugated chromophores‚ the electrons jump between energy levels that are extended pi orbitals‚ created by a series of alternating single and double bonds‚ often in aromatic systems. Common examples include retinal (used in the eye to detect light)‚ various food colorings‚ fabric dyes (azo compounds)‚ pH indicators‚ lycopene‚ β-carotene‚ and anthocyanins
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1 Measuring and calculating equilibrium constants Clearly‚ if the concentrations or pressures of all the components of a reaction are known‚ then the value of K can be found by simple substitution. Observing individual concentrations or partial pressures directly may be not always be practical‚ however. If one of the components is colored‚ the extent to which it absorbs light of an appropriate wavelength may serve as an index of its concentration. Pressure measurements are ordinarily able to measure
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CARIBBEAN EXAMINATIONS COUNCIL Caribbean Advanced Proficiency Examination CAPE ® CHEMISTRY SYLLABUS Unit 1 - effective for examinations from May/June 2007 Unit 2 - effective for examinations from May/June 2008 CXC A11/U2/06 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
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Transition Metals 1a) The d-orbitals of a free transition metal atom or ion are degenerate (all have the same energy.) However‚ when transition metals form coordination complexes‚ the d-orbitals of the metal interact with the electron cloud of the ligands in such a manner that the d-orbitals become non-degenerate (not all having the same energy.) The way in which the orbitals are split into different energy levels is dependent on the geometry of the complex. Crystal field theory can be used to predict
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HYDROCARBONS 365 UNIT 13 HYDROCARBONS Hydrocarbons are the important sources of energy. After studying this unit‚ you will be able to • • name hydrocarbons according to IUPAC system of nomenclature; recognise and write structures of isomers of alkanes‚ alkenes‚ alkynes and aromatic hydrocarbons; learn about various methods of preparation of hydrocarbons; distinguish between alkanes‚ alkenes‚ alkynes and aromatic hydrocarbons on the basis of physical and chemical properties; draw and
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