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