Key words

One way that students are often taught to approach a new title is to pick out the key words and work with these to understand how they should approach the assignment. A student described how she had used this approach at A level  

My strategy for dealing with the essay title is one that I learned at school. Basically, 1 pick out key words from the title and plan my structure around that. Then I try to write from this, putting together the introduction, the main body and lastly the conclusion. The trouble is that I keep getting blocked and can t get any further with the writing. When I try to write from the plan then I just drift off when I m writing. 

With the key words approach you pick out what seem to be the important parts of the question and ignore the linking words. The focus is on leaving out the less important linking words and picking out both the content key words (what the assignment is about) and the academic key words such as those in the list below  

One way of usefully working with the academic key words of the question is to spend some time thinking about the meanings of these words. Look at the above list. Look over some of the questions for written assignments in your course. 

Enzyme, p. 484 First-order reaction, p. 463 Half-life (fe), p. 466 Intermediate, p. 477 Molecularity of a reaction, p. 477 

Rate constant (A), p. 460 Rate-deteimining step, p. 478 Rate law, p. 460 Reaction mechanism, p. 477 Reaction order, p. 460 Reaction rate, p. 455 

Second-order reaction, p. 468 Termolecnlar reaction, p. 477 Transition state, p. 472 Unimolecitlar reaction, p. 477 

3 What are the advantages of measuring the initial rate of a reaction  

4 Can you suggest two reactions that are very slow (take days or longer to complete) and two reactions that are very fast (are over in minutes or seconds)  

Check Because 1 = 1 X 10 cm, we would expect much more mass in 1 m than 

Practice Exercise The density of the lightest metal, hthium (Li), is 5.34 X 10 kg/m. Convert the density to g/cm.  

The study of chemistry involves three basic steps observation, representation, and interpretation. Observation refers to measurements in the macroscopic world representation involves the use of shorthand notation symbols and equations for communication interpretations are based on atoms and molecules, which belong to the microscopic world. 

The scientific method is a systematic approach to research that begins with the gathering of information through observation and measurements. In the process, hypotheses, laws, and theories are devised and tested. 

Chemists study matter and the changes it undergoes. The substances that make up matter have unique physical properties that can be observed without changing their identity and unique chemical properties that, when they are demonstrated, do change the identity of the 

Alkynes are less common than alkenes, both in the laboratory and in living organisms, so we haven t covered them in great detail. The real importance of this chapter is that alkyne chemistry is a useful vehicle to look at the general strategies used in organic synthesis—the constmction of complex molecules in the laboratory. 

An alkyne is a hydrocarbon that contains a carbon-carbon triple bond. Alkyne carbon atoms are sp-hybridized, and the triple bond consists of one sp-sp a bond and two p-p tt bonds. There are relatively few general methods of alkyne synthesis. Two good ones ate the alkylation of an acetylide anion with a primary alkyl halide and the twofold elimination of HX from a vicinal dihalide. 

The chemistry of alkynes is dominated by electrophilic addition reactions, similar to those of alkenes. Alkynes react with HBr and HCl to yield vinylic halides and with Br2 and CI2 to yield 1,2-dihalides (vicinal dihalides). Alkynes can be hydrated by reaction with aqueous sulfuric acid in the presence of mercury(II) catalyst. The reaction leads to an intermediate enol that immediately tautomerizes to yield a ketone. Because the addition reaction occurs with Markovnikov regiochemistry, a methyl ketone is produced from a terminal alkyne. Alternatively, hydroboration-oxidation of a terminal alkyne yields an aldehyde. 

Alkynes can be reduced to yield alkenes and alkanes. Complete reduction of the triple bond over a palladium hydrogenation catalyst yields an alkane partial reduction by catalytic hydrogenation over a Lindlar catalyst yields a cis alkene. Reduction of the alkyne with lithium in ammonia yields a trans alkene. 

Terminal alkynes are weakly acidic. The alkyne hydrogen can be removed by a strong base such as Na NH2 to yield an acetylide anion. An acetylide anion acts as a nucleophile and can displace a halide ion from a primary alkyl halide in an alkylation reaction. Acetylide anions are more stable than either alkyl anions or vinylic anions because their negative charge is in a hybrid orbital with 50% s character, allowing the charge to be closer to the nucleus. 

Under certain conditions of carbon dioxide pressure and temperature, calcium carbonate breaks up to give lime and carbon dioxide according to the following expression  

Study the stability of the calcium carbonate ihombohedra in the temperature range (900 K, 1,500 K). Show the zones of stabiUty of lime and carbonate on the Pco J diagram. 

Show that neglecting the influence of the tenperature on standard enthalpy and entropy leads to a result close to exact calculatioa Plot the data in an axis system leading to lines. Evaluate the error made on the equilibrium pressure compared with the computed values in the first questioa Compute the minimal temperature of decomposition under a partial pressure of carbon dioxide of 1 atm. by the approximate method and the least-square line of the calculated points. Calculate the error made by the approximate method compared with the least-square hne of the computed values. 

We cany out the decomposition of this carbonate at 1,300 K under a partial pressure of carbon dioxide of 0.5 atm., the total pressure remaining 1 atm. with an inert gas. Compute the distance between these experimental and equilibrium conditions obtained by the preceding various methods and evaluate the errors made. Which method, for the thermodynamic study, do you suggest for the use of the result in a kinetic one  

An apparently inert gas can play a role in reactions rates. We now carry out the reaction of decomposition of calcium carbonate at 1,300 K, under a pure carbon dioxide pressme of 0.5 atm. Compute the new values of the distance between experimental and equihbrium conditions. 

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In this case the longest continuous chain has five carbon atoms the compound is named as a derivative of pentane The key word here is continuous It does not matter whether the carbon skeleton is drawn m an extended straight chain form or m one with many bends and turns All that matters is the number of carbons linked together m an uninterrupted sequence... 

Key words appear in boldface when they are introduced within the text. The term and its definition appear in the margin for quick review by the student. All keywords are also defined in the glossary. 

A HAZOP (Hazard and Operability Study) involves a fonual review of proeess and instrumentation diagrams by a speeialist team using a stmetured teehnique, based upon key words. These eomprise property words and guide words , e.g. as in Table 12.4. 

Progress in research and development in the wood-based industry and in the adhesive industry has shown many successes during the last decades. On the other hand, many industrial requirements still require considerable and important developments in this area. The main driving forces today are cheaper , quicker and more complex . The first two are caused by the heightened competition in the above-mentioned industries and the attempt to minimize costs while maintaining a certain level of product quality and performance. The key word more complex stands for new and specialized products and processes. Adhesives play a central role in wood-based panel production. The quality of bonding, and hence the properties of the wood-based panels, are determined mainly by the type and quality of the adhesive. Development in wood-based panels, therefore, is always linked to development in adhesives and resins. 

The following are key words you will run across in reading over the next several chapters. 

There may be some golden oldies among these r erences, but the key word is golden . Check out references 13 through 15 in particular. 

The use of any of the above techniques demands knowledge, experience, and flexibility. No prescriptive set of questions or key words or list is sufficient to cover all processes, hazards, and all impacted populations. As a research chemist reviews a chemistry and its potential application, there are advantages to maintaining an open mind when applying the various techniques designed to open up avenues of thought. The reader is referred to Chapter 7 for additional information and direction on the choice of process hazard review techniques. 

Key Words—Carbon nanotubes, vapor-grown carbon fibers, high-resolution transmission electron microscope, graphite structure, nanotube growth mechanism, toroidal network. 

Key Words—Single-wall, multi-wall, vibrational inodes, chiral nanotubes, electronic bands, tubule arrays. 

Key Words —Carbon nanotube, electronic properties, structural properties, strain energy, band gap, band structure, electronic structure. 

Key Words—Carbon, nanotubes, fiber, cobalt, catalysis, fullerenes, TEM. 

Key Words—Carbon nanotubes, pitch angle, helix angle, interlayer distance, carbon-carbon intralayer distance. 

Key Words—Carbon nanotubes, fullerenes, STM, fibers, nanostructures, vapor growth. 

Key Words —Carbon, molecular dynamics, torus, helix, graphitic forms. 

Key Words—Carbon fibers, nanoflbers, nanotubes, nanotube knees, fullerenes, tubules. 

Key Words—Nanotubes, pyrolytic carbon nanotubes, hemi-toroidal nanostructures. 

Key Words —Buckytubes, buckybundle, glow discharge, magnetic properties, transport properties. 

Key Words—Carbon nanotubes, scanning tunneling microscopy, spectroscopy, magnetoresistance, electrical resistivity, magnetic susceptibility. 

Key Words—Vibrations, infrared, Raman, disordered carbons, carbon nanotubes, normal modes. 

Key Words —Nanotubes, mechanical properties, thermal properties, fiber-reinforced composites, stiffness constant, natural resonance. 

Received 16 September 1994 accepted in revised form 9 November 1994) Key Words - Buckeytubes nanotubes graphene layers... 

Key Words—Nanoparticles, nanocapsules, rare-earth elements, iron, cobalt, nickel. 

Key Words—Graphite, fullerenes, HREM, nanostructures, electron irradiation. 

Key Words —Fullerenes, mass spectrometry, clusters, eieclroiiic shells, icosahedral layers. 

As a result of these merits thin layer chromatography finds application all over the world. The frequency of its application is documented in Figure 3. This CA search only includes those publications where TLC/HPTLC are included as key words. The actual application of the method is very much more frequent. The method is employed as a matter of course in many areas of quality control and routine monitoring of product purity. This was also true in the 1970s when the rapid development of high performance liquid chromatography (HPLG) led to a... 

Obviously, the key word in tliis chapter is identify. Material on identifying healUi hazards can be found in Chapters 9 and 10 of Part III. Tire identifying concerns for tliis cliapter primarily deal with accidents, and tlien accidents can take tlie form of either a chemical release or a disaster arising from a blast/fire/fragnicnt problem. 

Stich-tag, fixed day, key date, deadline, -wein, m. sample wine, -wort, n. heading catchword key word code word password cue. 

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