Zajęcia dokształcające z języka angielskiego w chemii nr
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Zajęcia dokształcające z języka angielskiego w chemii nr
Zajęcia dokształcające z języka angielskiego w chemii nr. 6 (opracował - P. Przybylski) Kontynuacja zajęć mających na celu wprowadzenie podstawowego słownictwa z zakresu chemii fizycznej szczególnie definicji podstawowych wielkości z zakresu chemii fizycznej (poruszane zagadnienia i przykłady tekstów zostały podane poniżej) – część druga. ELECTROCHEMICAL CELLS Przykład tekstu publikacji: Cathode materials for rechargeable lithium batteries GLOSSARY: Electrochemical cells – ogniwa elektrochemiczne electrodes – elektrody metallic conductor – przewodnik metaliczny electrolyte – elektrolit electrode compartment – komora elektrody to share – dzielić inert metal – metal inertny catalyst – katalizator salt bridge – mostek solny (klucz elektrolityczny) concentrated – stężony jelly – galaretka galvanic cell – ogniwo galwaniczne electricity – elektryczność spontaneous reaction – reakcja spontaniczna external source of current – zewnętrzne źródło prądu half-reactions – reakcje połówkowe (na elektrodach) oxidation – utlenienie reduction – redukcja species – cząstki redox reaction – reakcja redoks electron transfer – przeniesienie elektronu oxidation number – stopień utlenienia reducing agent – czynnik redukujący reductant – reduktor oxidizing agent – czynnik utleniający oxidant – utleniacz express – wyrażać conceptual – pojęciowy difference – różnica separated – rozdzielony release - uwolnić proceed – postępować, zachodzić (o reakcji chemicznej) anode – anoda cathode – katoda circuit – obwód higher potential – wyższy potencjał positive charge – dodatni ładunek negative charge – ujemny ładunek to be a supply with … – być zaopatrywanym w … necessary – konieczny, niezbędny immerse – zanurzać Daniell cell – ogniwo Daniella electrolyte concentration cell – ogniwo elektrolityczne stężeniowe gas electrodes – elektrody gazowe pressure – ciśnienie amalgam – amalgamat source of potential – źródło potencjału interface – obszar wzajemnego oddziaływania diffuse – dyfundują dilute solution – roztwór rozcieńczony bulkier – większe, o większej objętości at the same rate – z taką samą szybkością cell diagram – schemat zapisu ogniwa cell reaction – reakcja ogniwa assumption – założenie substract – odejmować cell potential – potencjał ogniwa chemical equilibrium – równowaga chemiczna accomplish – realizować volt – Volt amount - ilość electrical work – praca elektryczna measurement – pomiar reversibly – odwracalnie Gibbs energy – energia Gibbsa ensure – zapewnić constant composition – stały skład (chem.) balanced – zrównoważony to be poised for change – być gotowym na zmianę electromotive force /electromotance/ – siła elektromotoryczna Faraday constant – stała Faradaya Przykład fragmentu tekstu z czasopisma “Electrochemistry Communications” authored by Sun et al. 10 (2008) 1819-1822. Nano-wire networks of sulfur–polypyrrole composite cathode materials for rechargeable lithium batteries. Introduction The development of high energy density rechargeable batteries is of great importance due to the increasing demand of high energy for portable electronic and electrical applications. Elemental sulfur is very attractive as a cathode material for high specific energy rechargeable lithium cells based on the lithium–sulfur redox couple would yield a theoretical specific capacity of 1675 mA h g-1 and theoretical specific energy 2600 Wh kg-1 on the assumption of the complete reaction of lithium with sulfur to Li2S [1]. Furthermore, sulfur shows other advantages as cathode materials due to its abundance, low cost and environmental friendliness [2]. In spite of these advantages, the insulating nature of sulfur prevents full discharge of a Li/S battery with a 100% sulfur positive electrode at room temperature. Therefore, the cathode materials must be well combined with electrical and ionic conducting agent. Another problem putting off the application of sulfur as a cathode material in rechargeable lithium battery is its rapid capacity fading during cycling. The fading arrives from the fact that several lithium polysulfides, formed during discharge process, are dissolved in the liquid electrolytes. The use of absorbing agent is an approach to relieve the dissolving of polysulfides such as aluminium oxide, silicates, and vanadium oxides [3]. However, the effectiveness for improving cycle performance is unsatisfied due to their larger particle size and low specific surface area. Mesoporous carbon, active carbon, multiwalled carbon have better performance as absorbing agent in Li/S battery [4–6] due to their high porous structure and large surface area. Therefore, we target our work on finding a new absorbing agent with large surface area. PPy used to be studied as an additive to improve the performance of cathode and anode materials in lithium-ion batteries and lithium batteries [7–10]. Recently, a novel PPy was prepared through surfactant mediated approach which existed as nano-wire networks [11]. In this study, we used this PPy as a novel absorbing agent and investigated the effectiveness to improve electrochemical performance in lithium–sulfur batteries. Experimental Preparation of nano-wire networks of polypyrrole Polypyrrole nano-wire was prepared by a chemical polymerization method with cationic alkyltrimethylammonium surfactants (CTAB) as soft templates. Magnetically stirred solution of cooled (-2 °C) 0.2 M CTAB in 1.0 M HCl (200 ml) immediately turned very viscous when 0.26 M pyrrole were added. After vigorous stirring for 10 min, a solution of cooled (-2 °C) 0.06 M (NH4)2S2O8 in 1.0 M HCl (200 ml), was added all at once. The reaction mixture was stirred for 3 h at constant temperature (-2 °C). The resulting black precipitate of doped polypyrrole was suction filter in air and washed with copious amounts of deionized water and acetone. Suction filtration yielded a film on the surface of the filter. After dried in vacuum at temperatures of 80 °C for 12 h, the film was grinded into powder [11]. Electrochemical measurements The sulfur–polypyrrole (S–PPy) cathode slurry was made by mixing 60% composite material, containing about 40% sulfur and 20% PPy, with 30% acetylene black (AB) and 10% LA132 in propyl alcohol aqueous solvent to form a homogeneous slurry. Sulfur cathode slurry containing 60% sulfur powder, 30% AB and 10% LA132 was also prepared in the same way as described previously to compare with S–PPy composite. The slurries were spread onto aluminum foil substrates. The coated electrodes were dried in a vacuum oven at 55 °C for 24 h. Subsequently, the electrodes were cut to a 1 cm × 1 cm size. CR 2025 coin-type cells were assembled in an Ar-filled glove box (Mbraun, Unilab, Germany). The electrolyte used was 1 MLiCF3SO3 in a solvent of DOL:DME (1:1). The cells were galvanostatically discharged and charged on a LAND electrochemical in the range of 1.5 V–3.0 V. The chargeable current density was 0.4 mA cm-2 and the dischargeable current density was 0.1 mA cm-2. Cyclic voltammetry measurements were performed between 1.5 V–3.0 V at a scanning rate of 0.1 mV s-1. GLOSSARY: Nano-wire networks- sieci nanorurek sulfur–polypyrrole composite – kompozyt siarkowo-polipirolowy rechargeable lithium batteries – baterie akumulatorowe litowe high energy density – wysokiej gęstości energetycznej (ilość energii użytk. w jednostce objętości) portable – przenośny cathode material – materiał katodowy lithium–sulfur redox couple – para redoks lit-siarka capacity – pojemność advantages – korzyści, zalety abundance – abundancja, obfitość environmental friendliness – przyjazność środowisku, naturze insulate – izolować full discharge – całkowite rozładowanie at room temperature – w temperaturze pokojowej combined – połączony rapid – gwałtowny, bardzo szybki fad – przelotna, chwilowa polysulfides - polisulfidy liquid electrolytes – ciekłe elektrolity aluminium oxide – tlenek glinu silicates – krzemiany vanadium oxides – tlenki vanadu particle size – rozmiar cząstek mesoporous carbon – mezoporowaty węgiel active carbon – węgiel aktywny porous structure – struktura porowata surface – powierzchnia surfactant – surfaktant absorbing agent – środek absorbujący chemical polymerization – chemiczna polimeryzacja soft templates – miękka matryca Magnetically stirred – magnetycznie mieszane viscous – lepki at constant temperature – przy stałej temperaturze black precipitate – czarny osad suction filter - filtr próżniowy acetone – aceton dried – suszony grinded – rozkruszony powder – proszek slurry – zawiesina propyl alcohol – alcohol propylowy homogeneous – homogeniczny coated electrodes – pokryte elektrody galvanostatically discharged – galwanostatycznie rozładowane the chargeable current density – gęstość prądu ładowania dischargeable current density – gęstość prądu rozładowania Cyclic voltammetry – cykliczna woltametria scanning rate – szybkość skanowania Druga część zajęć ma na celu wprowadzenie podstawowego słownictwa z zakresu chemii koordynacyjnej i katalizy. COORDINATION CHEMISTRY CATALYSIS Wybrane fragmenty z książki p.t. “Comprehensive Coordination Chemistry” ed. G. Wilkinson,. R.D. Gillard and J.A. McCleverty, Pergamon Press, Oxford, 1987. GLOSSARY: coordination compound – związek koordynacyjny coordination number – liczba koordynacyjna coordination geometry – geometria koordynacji uni-, bi-, poly-dentate ligands – ligandy jedno-, dwu- i wielokleszczowe complex compounds – związki kompleksowe complexes – kompleksy transition metal salt – sól metalu przejściowego oxidation state – stopień utlenienia primary/ secondary valence – wartościowość pierwszorzędowa (główna)/ drugorzędowa metal ion – jon metalu bonded - związany counterion – przeciwjon orientation in space – zorientowanie w przestrzeni metal-bound groups – grupy wiążące metal geometric structure – struktura geometryczna Lewis acid – kwas Lewisa Broensted base – zasada Broensteda electron pair acceptor – akceptor pary elektronowej proton acceptor – akceptor protonu ligands – ligandy macromolecules – makromolekuły to donate an electron pair – oddawać parę elektronową organometallic compounds – związki metaloorganiczne single point of attachment – jeden punkt przyłączenia several – kilka donor atoms – atomy donorowe chelate complex – kompleks chelatowy stable – stabilny variety – różnorodność carbon donor atom – donorowy atom węgla chelate ring – pierścień chelatowy four-membered chelate ring – czteroczłonowy pierścień chelatowy cyclic compounds – związki cykliczne macrocyclic - makrocykliczny bicyclic proligands – bicykliczne proligandy to encapsulate a metal ion – zamknąć szczelnie jon metalu cryptand – kryptand bridging arrangement – mostkowe ułożenie f-block elements – pierwiastki bloku f structural isomers – izomery strukturalne more favourable energetically – bardziej energetycznie uprzywilejowany regular geometry – regularna geometria distortion – zniekształcenie, odkształcenie homo/heteroleptic – homo/heteroleptyczny bulky ligand – duży, objętościowy ligand prevent – zapobiegać linear – liniowy amide ligand – ligand amidowy planar structure – struktura płaska pyramidal – piramidalny square planar – płasko-kwadratowe tetrahedral – tetraedryczne trigonal plane – trygonalna płaska trigonal bipyramidal – bipiramida trygonalna square pyramidal – piramida kwadratowa octahedral – oktaedryczny ligand-ligand interaction – odziaływanie ligand-ligand trigonal prismatic – pryzmat trygonalny tetragonal distortion – odkształcenie tetragonalne trigonal distortion – odkształcenie trygonalne fourfold rotation axis – oś czterokrotna obrotu dodecahedral – dodekaedryczny square antiprismatic – antypryzmat kwadratowy icosahedral – ikozaedryczny geometric isomerism – izomeria geometryczna optical isomerism – izomeria optyczna adjacent – przyległy, sąsiedni facial - facjalny meridional - południkowy Fragmenty tekstu “Types of catalytic reactions”, http://www.chemguide.co.uk/physical/catalysis/introduction.html Types of catalytic reactions Catalysts can be divided into two main types - heterogeneous and homogeneous. In a heterogeneous reaction, the catalyst is in a different phase from the reactants. In a homogeneous reaction, the catalyst is in the same phase as the reactants. What is a phase? If you look at a mixture and can see a boundary between two of the components, those substances are in different phases. A mixture containing a solid and a liquid consists of two phases. A mixture of various chemicals in a single solution consists of only one phase, because you can't see any boundary between them. You might wonder why phase differs from the term physical state (solid, liquid or gas). It includes solids, liquids and gases, but is actually a bit more general. It can also apply to two liquids (oil and water, for example) which don't dissolve in each other. You could see the boundary between the two liquids. If you want to be fussy about things, the diagrams actually show more phases than are labelled. Each, for example, also has the glass beaker as a solid phase. All probably have a gas above the liquid - that's another phase. We don't count these extra phases because they aren't a part of the reaction. Heterogeneous catalysis This involves the use of a catalyst in a different phase from the reactants. Typical examples involve a solid catalyst with the reactants as either liquids or gases. How the heterogeneous catalyst works (in general terms) Most examples of heterogeneous catalysis go through the same stages: One or more of the reactants are adsorbed on to the surface of the catalyst at active sites. Adsorption is where something sticks to a surface. It isn't the same as absorption where one substance is taken up within the structure of another. Be careful! An active site is a part of the surface which is particularly good at adsorbing things and helping them to react. There is some sort of interaction between the surface of the catalyst and the reactant molecules which makes them more reactive. This might involve an actual reaction with the surface, or some weakening of the bonds in the attached molecules. The reaction happens. At this stage, both of the reactant molecules might be attached to the surface, or one might be attached and hit by the other one moving freely in the gas or liquid. The product molecules are desorbed. Desorption simply means that the product molecules break away. This leaves the active site available for a new set of molecules to attach to and react. A good catalyst needs to adsorb the reactant molecules strongly enough for them to react, but not so strongly that the product molecules stick more or less permanently to the surface. Silver, for example, isn't a good catalyst because it doesn't form strong enough attachments with reactant molecules. Tungsten, on the other hand, isn't a good catalyst because it adsorbs too strongly. Metals like platinum and nickel make good catalysts because they adsorb strongly enough to hold and activate the reactants, but not so strongly that the products can't break away. Examples of heterogeneous catalysis The hydrogenation of a carbon-carbon double bond The simplest example of this is the reaction between ethene and hydrogen in the presence of a nickel catalyst. In practice, this is a pointless reaction, because you are converting the extremely useful ethene into the relatively useless ethane. However, the same reaction will happen with any compound containing a carbon-carbon double bond. One important industrial use is in the hydrogenation of vegetable oils to make margarine, which also involves reacting a carbon-carbon double bond in the vegetable oil with hydrogen in the presence of a nickel catalyst. Ethene molecules are adsorbed on the surface of the nickel. The double bond between the carbon atoms breaks and the electrons are used to bond it to the nickel surface. Hydrogen molecules are also adsorbed on to the surface of the nickel. When this happens, the hydrogen molecules are broken into atoms. These can move around on the surface of the nickel. If a hydrogen atom diffuses close to one of the bonded carbons, the bond between the carbon and the nickel is replaced by one between the carbon and hydrogen. That end of the original ethene now breaks free of the surface, and eventually the same thing will happen at the other end. As before, one of the hydrogen atoms forms a bond with the carbon, and that end also breaks free. There is now space on the surface of the nickel for new reactant molecules to go through the whole process again. Note: Several metals, including nickel, have the ability to absorb hydrogen into their structure as well as adsorb it on to the surface. In these cases, the hydrogen molecules are also converted into atoms which can diffuse through the metal structure. This happens with nickel if the hydrogen is under high pressures, but I haven't been able to find any information about whether it is also absorbed under the lower pressures usually used for these hydrogenation reactions. I have therefore stuck with the usual explanation in terms of adsorption. Catalytic converters Catalytic converters change poisonous molecules like carbon monoxide and various nitrogen oxides in car exhausts into more harmless molecules like carbon dioxide and nitrogen. They use expensive metals like platinum, palladium and rhodium as the heterogeneous catalyst. The metals are deposited as thin layers onto a ceramic honeycomb. This maximises the surface area and keeps the amount of metal used to a minimum. Taking the reaction between carbon monoxide and nitrogen monoxide as typical: In the same sort of way as the previous example, the carbon monoxide and nitrogen monoxide will be adsorbed on the surface of the catalyst, where they react. The carbon dioxide and nitrogen are then desorbed. The use of vanadium(V) oxide in the Contact Process During the Contact Process for manufacturing sulphuric acid, sulphur dioxide has to be converted into sulphur trioxide. This is done by passing sulphur dioxide and oxygen over a solid vanadium(V) oxide catalyst. This example is slightly different from the previous ones because the gases actually react with the surface of the catalyst, temporarily changing it. It is a good example of the ability of transition metals and their compounds to act as catalysts because of their ability to change their oxidation state. The sulphur dioxide is oxidised to sulphur trioxide by the vanadium(V) oxide. In the process, the vanadium(V) oxide is reduced to vanadium(IV) oxide. The vanadium(IV) oxide is then re-oxidised by the oxygen. This is a good example of the way that a catalyst can be changed during the course of a reaction. At the end of the reaction, though, it will be chemically the same as it started. Homogeneous catalysis This has the catalyst in the same phase as the reactants. Typically everything will be present as a gas or contained in a single liquid phase. The examples contain one of each of these . . . Examples of homogeneous catalysis The reaction between persulphate ions and iodide ions This is a solution reaction that you may well only meet in the context of catalysis, but it is a lovely example! Persulphate ions (peroxodisulphate ions), S2O82-, are very powerful oxidising agents. Iodide ions are very easily oxidised to iodine. And yet the reaction between them in solution in water is very slow. If you look at the equation, it is easy to see why that is: The reaction needs a collision between two negative ions. Repulsion is going to get seriously in the way of that! The catalysed reaction avoids that problem completely. The catalyst can be either iron(II) or iron(III) ions which are added to the same solution. This is another good example of the use of transition metal compounds as catalysts because of their ability to change oxidation state. For the sake of argument, we'll take the catalyst to be iron(II) ions. As you will see shortly, it doesn't actually matter whether you use iron(II) or iron(III) ions. The persulphate ions oxidise the iron(II) ions to iron(III) ions. In the process the persulphate ions are reduced to sulphate ions. The iron(III) ions are strong enough oxidising agents to oxidise iodide ions to iodine. In the process, they are reduced back to iron(II) ions again. Both of these individual stages in the overall reaction involve collision between positive and negative ions. This will be much more likely to be successful than collision between two negative ions in the uncatalysed reaction. What happens if you use iron(III) ions as the catalyst instead of iron(II) ions? The reactions simply happen in a different order. The destruction of atmospheric ozone This is a good example of homogeneous catalysis where everything is present as a gas. Ozone, O3, is constantly being formed and broken up again in the high atmosphere by the action of ultraviolet light. Ordinary oxygen molecules absorb ultraviolet light and break into individual oxygen atoms. These have unpaired electrons, and are known as free radicals. They are very reactive. The oxygen radicals can then combine with ordinary oxygen molecules to make ozone. Ozone can also be split up again into ordinary oxygen and an oxygen radical by absorbing ultraviolet light. This formation and breaking up of ozone is going on all the time. Taken together, these reactions stop a lot of harmful ultraviolet radiation penetrating the atmosphere to reach the surface of the Earth. The catalytic reaction we are interested in destroys the ozone and so stops it absorbing UV in this way. Chlorofluorocarbons (CFCs) like CF2Cl2, for example, were used extensively in aerosols and as refrigerants. Their slow breakdown in the atmosphere produces chlorine atoms - chlorine free radicals. These catalyse the destruction of the ozone. This happens in two stages. In the first, the ozone is broken up and a new free radical is produced. The chlorine radical catalyst is regenerated by a second reaction. This can happen in two ways depending on whether the ClO radical hits an ozone molecule or an oxygen radical. If it hits an oxygen radical (produced from one of the reactions we've looked at previously): Or if it hits an ozone molecule: Because the chlorine radical keeps on being regenerated, each one can destroy thousands of ozone molecules. Autocatalysis The oxidation of ethanedioic acid by manganate(VII) ions In autocatalysis, the reaction is catalysed by one of its products. One of the simplest examples of this is in the oxidation of a solution of ethanedioic acid (oxalic acid) by an acidified solution of potassium manganate(VII) (potassium permanganate). The reaction is very slow at room temperature. It is used as a titration to find the concentration of potassium manganate(VII) solution and is usually carried out at a temperature of about 60°C. Even so, it is quite slow to start with. The reaction is catalysed by manganese(II) ions. There obviously aren't any of those present before the reaction starts, and so it starts off extremely slowly at room temperature. However, if you look at the equation, you will find manganese(II) ions amongst the products. More and more catalyst is produced as the reaction proceeds and so the reaction speeds up. You can measure this effect by plotting the concentration of one of the reactants as time goes on. You get a graph quite unlike the normal rate curve for a reaction. Most reactions give a rate curve which looks like this: Concentrations are high at the beginning and so the reaction is fast - shown by a rapid fall in the reactant concentration. As things get used up, the reaction slows down and eventually stops as one or more of the reactants are completely used up. An example of autocatalysis gives a curve like this: You can see the slow (uncatalysed) reaction at the beginning. As catalyst begins to be formed in the mixture, the reaction speeds up - getting faster and faster as more and more catalyst is formed. Eventually, of course, the rate falls again as things get used up. Warning! Don't assume that a rate curve which looks like this necessarily shows an example of autocatalysis. There are other effects which might produce a similar graph. For example, if the reaction involved a solid reacting with a liquid, there might be some sort of surface coating on the solid which the liquid has to penetrate before the expected reaction can happen. A more common possibility is that you have a strongly exothermic reaction and aren't controlling the temperature properly. The heat evolved during the reaction speeds the reaction up. GLOSSARY: catalytic reaction – reakcja katalityczna catalyst – katalizator divide – dzielić heterogeneous – heterogeniczny homogeneous – homogeniczny reactants – reagenty solid/liquid/gas phase – faza stała/ciekła/gazowa mixture – mieszanina component - składnik solution – roztwór oil – oliwa, olej fussy – wybredny, grymaśny glass beaker – szklana zlewka adsorbed – zaadsorbowany active site – miejsce aktywne absorption – absorpcja to react – reagować surface – powierzchnia weakening of the bonds – osłabienie wiązań desorption – desorpcja silver – srebro tungsten - wolfram platinum – platyna nickel – nikiel pointless reaction – bezcelowa reakcja industrial – przemysłowy vegetable oil – olej roślinny break free - uwolnić under high pressure – pod wysokim ciśnieniem poisonous – trujący carbon monoxide – tlenek węgla nitrogen oxides – tlenki azotu carbon dioxide – dwutlenek węgla nitrogen – azot palladium – pallad rhodium – rod are deposited – są osadzone thin layer – cienka warstwa ceramic honeycomb – ceramiczny plaster miodu to maximize the surface – maksymalizować powierzchnię vanadium (V) oxide – tlenek wanadu (V) Contact Process – metoda kontaktowa (produkcji H2SO4) sulphuric acid – kwas siarkowy sulphur dioxide – dwutlenek siarki temporarily – tymczasowo change the oxidation state – zmiana stopnia utlenienia oxidised – utleniony reduced – zredukowany persulphate /peroxodisulphate ion – jon nadsiarczanowy/nadtlenodwusiarczanowy oxidizing agent – środek utleniający iodide ion – jon jodkowy iodine – jod equation – równanie iron – żelazo suplphate ions – jony siarczanowe ozone – ozon in the high atmosphere – wyższych partiach atmosfery ultraviolet light – światło ultrafioletowe free radicals – wolne rodniki reactive – reaktywny aerosol – aerozol refrigerant – czynnik chłodniczy in two stages – w dwóch etapach chlorine atoms – atomy chloru chlorine free radicals – wolne rodniki chlorowe autocatalysis – autokataliza oxalic acid – kwas szczawiowy potassium permanganate – nadmanganian potasu speeds up – przyspieszać