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Chemistry of Cars unit_7_chemistry_of_cars
Chemistry of Cars unit_7_chemistry_of_cars

... rhodium to help reduce the NOx emissions. When an NO or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming ...
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Carboxylic Acid Derivatives and Nitrogen Cpds
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... careful acidification, some yellow crystals are produced together with L, C7H7NO2. L can be produced from 4-nitromethylbenzene in a 2-step reaction via an intermediate M. 4-nitromethylbenzene is first heated with tin in the presence of concentrated hydrochloric acid to form M, and then followed by a ...
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Chapter 10
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No Slide Title

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energy and rates practice test answers

PPT: Chemical Reactions and Equations
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Name……………………………………............................. Index number
Name……………………………………............................. Index number

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Many thermal and chemical reactions occur during the roasting
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Chapter 11.1: Describing Chemical Reactions
Chapter 11.1: Describing Chemical Reactions

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... Standard molar entropies of pure substances are always positive quantities. Aqueous ions may have negative entropy values. As a group, gases tend to have higher entropies than liquids. An increase in the number of moles of a gas also leads to a higher entropy and vice versa. As a molecule becomes mo ...
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Chapter 4: Aqueous Reactions and Solution
Chapter 4: Aqueous Reactions and Solution

... reactions and our abilities to predict the products of and write balanced chemical equations for a variety of chemical reactions. We will also review solution terminology, properties of solutions and the concept of molarity. We will then be able extend our ability to do stoichiometric calculations t ...
physics/0010052 PDF
physics/0010052 PDF

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types of reactions

... state where 2 exactly opposite chemical reactions are occurring at the same place, same time, and same rate (speed) where reactions continuously occur •Two opposing forces are being exerted but they are in a state of balance •Amounts of all chemical entities are constant but do not ...
examples of chemical and physical reactions.
examples of chemical and physical reactions.

... 1. Paint or grease. This prevents water or oxygen reaching the iron. However, this is only a temporary step since paint can flake off and grease can be rubbed off quite easily. Bikes are often painted of greased to prevent rust, since this is the cheapest method of prevention. 2. Plastic. Plastic is ...
enthalpy worksheet
enthalpy worksheet

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chapter 4 lecture slides

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Lewis acid catalysis



In Lewis acid catalysis of organic reactions, a metal-based Lewis acid acts as an electron pair acceptor to increase the reactivity of a substrate. Common Lewis acid catalysts are based on main group metals such as aluminum, boron, silicon, and tin, as well as many early (titanium, zirconium) and late (iron, copper, zinc) d-block metals. The metal atom forms an adduct with a lone-pair bearing electronegative atom in the substrate, such as oxygen (both sp2 or sp3), nitrogen, sulfur, and halogens. The complexation has partial charge-transfer character and makes the lone-pair donor effectively more electronegative, activating the substrate toward nucleophilic attack, heterolytic bond cleavage, or cycloaddition with 1,3-dienes and 1,3-dipoles.Many classical reactions involving carbon–carbon or carbon–heteroatom bond formation can be catalyzed by Lewis acids. Examples include the Friedel-Crafts reaction, the aldol reaction, and various pericyclic processes that proceed slowly at room temperature, such as the Diels-Alder reaction and the ene reaction. In addition to accelerating the reactions, Lewis acid catalysts are able to impose regioselectivity and stereoselectivity in many cases.Early developments in Lewis acid reagents focused on easily available compounds such as TiCl4, BF3, SnCl4, and AlCl3. The relative strengths of these (and other) Lewis acids may be estimated from NMR spectroscopy by the Childs method or the Gutmann-Beckett method. Over the years, versatile catalysts bearing ligands designed for specific applications have facilitated improvement in both reactivity and selectivity of Lewis acid-catalyzed reactions. More recently, Lewis acid catalysts with chiral ligands have become an important class of tools for asymmetric catalysis.Challenges in the development of Lewis acid catalysis include inefficient catalyst turnover (caused by catalyst affinity for the product) and the frequent requirement of two-point binding for stereoselectivity, which often necessitates the use of auxiliary groups.
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