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01.14 ...what we’re going to want to do
01.26 …drawn on the paper
02.28 ...half the distance
21 Work with a partner. Make up 5 questions relying on the video and then ask
your partner. Alternatively, you could work in several teams compiling questions
together and then delivering them to another team. The team with the largest
number of correct answers wins!
Vocabulary Boost
22 Write the full definitions for the terms provided below.
For your definitions, use the structure:
A is B that / which / where C, where A is a term, B is a class or category, and C is
a description.
Remember: that normally goes with essential information, which introduces
nonessential one, and where is linked to location or space.
Terms: chromatography; paper chromatography; stationary phase; mobile phase;
retention value / retention factor; solvent; solute; solvent front; baseline; conditions;
ratio; value; distance; bands; eluent; to separate; to travel
23 Give the English equivalents for the following terms.
1. эксклюзионная хроматография
2. выделение, изъятие
3. безводный
4. извлекать из адсорбента
5. элюирование, вымывание
6. водный, на водной основе
7. проникать, просачиваться
8. наполненная колонка
9. неподвижный
10. исключить, вытеснять
11. проба
12. состав, структура
13. селективная способность
14. лиганд
15. проводимость
16. вещество, обладающее буферными свойствами
17. связующая способность
18. связывание
19. взаимосвязь, обмен
20. сходство, близость
21. смещение, вытеснение
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24 Translate the following fragments from Russian into English.
Option 1
Хроматография — метод разделения, анализа и исследования смесей веществ,
основанный на различном распределении веществ в динамических условиях между
подвижной и неподвижной фазами. Метод предложен русским учёным М. С. Цветом в
1903 году. В зависимости от агрегатного состояния подвижной фазы системы, в которой
проводят разделение смеси веществ на отдельные компоненты, различают
газоадсорбционную, газожидкостную хроматографию и жидкостную хроматографию.
Хроматографию классифицируют также по механизму разделения: адсорбционная,
ионообменная, разделительная (распределительная), эксклюзионная. В адсорбционной
хроматографии разделение осуществляется в результате взаимодействия вещества с
адсорбентами (например, силикагелем, оксидом алюминия и др.), имеющими на
поверхности активные центры. В разделительной (распределительной) хроматографии
вещества разделяются из-за различной растворимости компонентов смеси. Неподвижный
растворитель обычно закреплён на твёрдом носителе (см. бумажная хроматография).
Option 2
Хроматография – важнейший аналитический метод. Хроматографическими
методами можно определять газообразные, жидкие, и твердые вещества с молекулярной
массой от единиц до 10
6
. Это могут быть неорганические вещества, например ионы
металлов, изотопы водорода, и органические – белки, синтетические полимеры и т.д. С
помощью хроматографии получена обширная информация о строении и свойствах
органических соединений многих классов. Хроматографию с успехом применяют в
исследовательских и клинических целях в различных областях биохимии и медицины; в
фармацевтике, криминалистике,
пищевой промышленности, для мониторинга
окружающей среды. Универсальность, экспрессность, чувствительность метода
обусловливают частое использование хроматографии в аналитических целях. В
зависимости от природы взаимодействия, обусловливающего распределение
компонентов между элюентом и неподвижной фазой, различают следующие основные
виды хроматографии: адсорбционную, распределительную, ионообменную,
эксклюзионную (молекулярно-ситовую или гель-проникающую) и осадочную.
Option 3
Хроматография – это физико-химический метод разделения веществ, основанный на
распределении компонентов между двумя фазами – подвижной и неподвижной.
Неподвижной фазой обычно служит твердое вещество (сорбент) или пленка жидкости,
нанесенная на твердое вещество. Подвижная фаза представляет собой жидкость или газ,
протекающий через неподвижную фазу. Компоненты анализируемой смеси вместе с
подвижной фазой перемещаются вдоль стационарной фазы, которую обычно помещают
в колонку (стеклянную или металлическую трубку). Если молекулы разных компонентов
разделяемой смеси обладают различной адсорбируемостью или растворимостью, то
время их пребывания в неподвижной фазе, следовательно, и средняя скорость
передвижения по колонке различны. Одни компоненты остаются в верхнем слое
сорбента, другие, с меньшей адсорбируемостью, оказываются в нижней части колонки,
некоторые покидают колонку вместе с подвижной фазой. Так достигается разделение
компонентов. Хроматография – динамический метод, связанный с многократным
повторением сорбционных и десорбционных процессов, так как разделение происходит в
потоке подвижной фазы. Это обеспечивает эффективность хроматографического метода
по сравнению с методами сорбции в статических условиях.
Option 4
Хроматография - физико-химический метод разделения и анализа смесей, основанный
на распределении их компонентов между двумя фазами - неподвижной и подвижной
(элюент), протекающей через неподвижную. Хроматографический анализ является
критерием однородности вещества: если каким-либо хроматографическим способом
анализируемое вещество не разделилось, то его считают однородным (без примесей). С
помощью хроматографии возможны: разделение сложных смесей органических и
неорганических веществ на отдельные компоненты, очистка веществ от примесей,
концентрирование веществ из сильно разбавленных растворов, качественный и
количественный анализ исследуемых веществ.
62
Принципиальным отличием хроматографических методов от других физикохимических методов анализа является возможность разделения близких по свойствам
веществ. После разделения компоненты анализируемой смеси можно идентифицировать
(установить природу) и количественно определять (массу, концентрацию) любыми
химическими, физическими и физико-химическими методами.
(по Гиндуллина Т.М. - Хроматографические методы анализа)
Discussion
25 Discuss with the partner if the statements below are TRUE or FALSE.
1. Chromatography is a means of separating and tentatively identifying the
components of a mixture
2. The major advantage of high-performance liquid chromatography is that
the entire process takes place at room temperature.
3. The technique of thin-layer chromatography incorporates a liquid
stationary phase and a moving gas phase to effect the separation of the constituents in
a mixture.
4. Objects absorb certain portions of visible light and transmit or reflect
others, hence, providing the visual indicator of color.
5. The selective absorption of a substance is measured by an instrument
called the chromatogram
6. Infrared spectrophotometry allows for the identification of different
materials because different organic substances always produce distinctive infrared
spectra.
7. The unique feature of mass spectrometry is that under carefully controlled
conditions, no two substances produce the same fragmentation pattern.
8. The benefit of gas chromatography is that any solid material can be
readily dissolved in a solvent for injection into the gas chromatograph.
26 Discuss the questions below with your partner or your teacher.
1. What is chromatography?
2. What are the 4 types of chromatography within the two main categories?
3. What is the stationary phase in paper chromatography?
4. What is the moving phase in paper chromatography?
5. What is a chromatogram?
6. What is the stationary phase of column chromatography?
7. What is elution?
8. What is gas chromatography useful for?
9. Describe the procedure in paper chromatography.
10. Describe the process of thin layer chromatography.
11. Describe the procedure in column chromatography.
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27 Use the mindmap below to give an overview on chromatography.
(in cooperation with Eduard Sayfulin, group 08501)
64
28 Watch one of the educational videos on chromatography techniques and
procedures issued by Massachusetts Institute of Technology (MIT).
Note down the key information. Figure out the trickiest and hard-to-understand
academic collocations related to the topic; rewrite them in simple plain English.
Devise a PPT presentation summarizing 1) the main information given in the
video; 2) your rewriting experience in terms of successful / unsuccessful
strategies.
To choose a video, follow the link: https://disk.yandex.ru/d/8dJEOdW6SqrBFg
The video transcripts are provided.
Further Watching and Speaking
29 Watch the video about column chromatography and answer the questions
below. Follow the link: https://disk.yandex.ru/i/vXOawYnmqFhuZA
Before watching, take a look at the glossary below.
Glossary (in the order of appearance)
In a large scale В больших масштабах
Active ingredient Активное вещество
To set up Устанавливать
Opening Отверстие, горлышко
Glassware Стеклянная посуда
Cotton ball Ватный шарик
Fine layer of sand Тонкий слой песка
To ram Оборачивать, утрамбовывать
To pack / to load Загружать (в колонну)
Tilted / slanted / crooked / in the slanted
manner
Perpendicular to Перпендикулярно чему-н.
Parallel to Параллельно чему-н.
Silica Силикагель
Bands Хроматографические полосы / зоны
To crack Потрескаться
To flow Течь
To redraw Перерисовать
Even layer Ровный слой
Distinct bands Четкие полосы
To proceed Здесь – происходить
To collect Собирать
Polarity Полярность
Fraction Фракция
Efficient Эффективный
To prep Подготавливать
Initial stages Начальные стадии
Не перпендикулярно, под углом < или
> 90о
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Questions
1. What is the practical application of column chromatography (CC)?
2. What is used for filtering in CC? How should it be loaded into the column? Why
is filtering necessary?
3. What are the constituent parts of chromatography column?
4. How is the eluent applied in СС?
5. What are the stationary and the mobile phases in СС?
6. What do we observe upon adding a solvent?
7. How do we add silica? Why is it important?
8. What principle is the separation of fractions based on?
Check Yourself
1 Complete the gaps with the words from the box below.
gas / liquid flask application travel collect eluent
silica plates gas bands dried liquid solid size medicinal charge
1. Exclusion chromatography is based on the… of molecules.
2. The practical… of column chromatography is preparing a pure form of a drug
in … industry.
3. While performing column chromatography, you can observe different…, which
are different compounds that... at different rates.
4. After you see the bands, you begin to… each separate fraction into the...
5. A solvent in chromatography is often called...
6. In partition chromatography, they normally use…
7. Most often, they use… as a stationary phase in TLC.
8. In gas solid chromatography, mobile phase is… and stationary phase is...
9. In ion exchange chromatography, they separate molecules based on their...
10. In supercritical fluid, they work with… molecules.
2 Match a phrase in A with a phrase in B to form a complete sentence
AB
11. Chromatography is.....
12. Chromatography involves .... b) ......distance traveled by the solute from
13. Stationary phase can be ..... c) ......spotted on the origin line
14. The mixture to be separated is
placed.....
15. Mobile phase can be ..... e) ......the solvent used and the composition
16. The mobile phase moves
along the stationary phase, ......
17. Attractions of components to g) ....by capillary action.
a) ....retention factor (Rf)
the origin/distance traveled by the
solvent from the origin
d) .....a stationary phase and a mobile
phase
of filter paper
f) .....group of techniques used to separate
colored mixtures into their component
parts (often used for blood or drinking
water analyses)
66
mobile or stationary phase is due
to ....
18. In paper chromatography, the
sample is ....
19. Once sample has been
spotted, ......
20. Components of mixture move
.....
21. The movement of components
is characterized in terms of a .....
22. Retention (Rf) depends on ...... l) .....liquid or gas
23. The solution in paper
chromatography move up the
paper ......
24. The formula for calculating the
Rf value is .....
3 Fill in the gaps in the following fragment. Use the word given in capitals at the
end of each line to form a word that fits in the space in the same line.
Chromatography was originally developed by the Russian
botanist Michael Tsvet in 1903 for the 25_____ of colored plant
pigments by percolating a petroleum ether extract through a
glass column 26_____ with powdered calcium carbonate. It is
now, in general, the most widely used separation technique in
analytical chemistry having 27_____ into a number of related
but quite different forms that enable the components of complex
mixtures of organic or 28_____components to be separated
and 29_____. A chromatographic separation involves the
placing of a sample onto a liquid or solid stationary phase and
passing a liquid or 30_____ mobile phase through or over it, a
process known as 31______. Sample components, or
32______, whose distribution ratios between the two phases
differ will migrate (be 33______ ) at different rates, and this
differential rate of migration will lead to their separation over a
period of time and distance.
28-33 Excellent. You can use the vocabulary from Unit 3 very well.
23-27 Quite good, but you need to learn some words.
13-22 Not bad, but you need to be more persistent in your everyday practice.
0-12 This is hard for you. Learn the vocabulary from the Unit 3 and do the tasks
again
h) ......bottom edge of paper is put in
solvent and solvent moves up paper;
when solvent front reaches sample, the
sample components are attracted to
either stationary or mobile phase
i) .....solid or liquid
j) ......intermolecular interactions
k) .....on the stationary phase
m) .....at different rates and separate,
creating chromatogram
n) .......carrying some or all of the mixture
with it, resulting in the separation of the
mixture components
SEPARATE
PACK
DEVELOP
ORGANIC
QUANTIFY
GAS
ELUTE
SOLUTION
ELUTED
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Unit 4
ELECTROCHEMICAL METHODS OF ANALYSIS
Learning objectives
In Unit 4, you will learn to talk about electrochemical methods, define their
main types, and to describe the procedures of potentiometry, coulometry,
and voltammetry.
Michael Faraday is an English scientist who
contributed to the study of electromagnetism and
electrochemistry. His main discoveries include the
principles underlying electromagnetic induction,
diamagnetism, and electrolysis.
Michael Faraday
Warming up
1 Watch the video about the basic principle of electrochemistry and answer the
questions. Follow the link: https://disk.yandex.ru/i/NJwWn-z1dsGdQg
Electrochemistry: Professor Dave Explains
Part 1
1. Who and when devised the first battery?
2. Characterize the chemical process inside a voltaic electrochemical cell?
3. Where do the oxidation and reduction processes take place?
4. What is generated in a voltaic cell as a result of the chemical process
described above?
5. Describe the arrangement of the cell.
68
6. Describe the path of ions on cathode and anode. What are these ions and
where do they flow?
Part 2
7. What specific notation is used to characterize the voltaic cell?
8. What is the function of the least common multiple of electrons?
9. What is electron flow?
10. Define the cell potential (Ecell). How can we calculate it?
11. Characterize the reduction potentials for fluorine, lithium, and sodium.
12. What is the correlation between Ecell and the electrical current a voltaic cell
can generate?
Part 3
13. Define Gibbs energy.
14. The standard cell potential is Ecell under standard conditions. How is it
calculated?
15. Pause the video at 5:25 and do the problems. Then check your answers.
2 Work with the partner and formulate the basic facts for electrochemistry as 3
separate coherent sentences using the information from the video and your
background in chemistry. Then fill in the gaps in the text below to complete the
basic facts about electrochemistry and electrochemical methods.
Electrochemistry: Background
Electrochemistry involves the concept of electroconductivity, that is, an ability of
ions to conduct the electrical current. Electrochemistry is the b____(1) of chemistry that
studies converting chemical energy to electrical energy and then to light or heat. Two
electrodes – an a____ (2), which accepts electrons and serves as a r_____ (3), and
c____ (4), which donates electrons and serves as an o_____ (5), are the working
materials of any electrochemical system.
Additionally, an electrochemical system includes a s___ b____(6), which is a
barrier allowing the ions to flow. The electrodes are submerged into electrolytic
s____(7) containing salts that can ionize.
A p_____ (8) is an inner force that can initiate an electrochemical process. As a
result, an electrical c_____ (9) can be generated.
Potentiometry, amperometry, voltammetry, and coulometry are the main
t____(10) of electrochemical methods.
(devised in cooperation with group 08601b)
Reading and Speaking
3 Read a short introductory text and fill in the chart below. Then discuss with
your partner what the concept of electrochemistry is and where it can be applied.
The Concept of Electrochemistry
Electrochemistry is the branch of chemistry concerned with the interrelation of
electrical and chemical effects. A large part of this field deals with the study of chemical
changes caused by the passage of an electric current and the production of electrical
energy by chemical reactions. In fact, the field of electrochemistry encompasses a huge
array of different phenomena (e.g., electrophoresis and corrosion), devices
(electrochromic displays, electroanalytical sensors, batteries, and fuel cells), and
69
technologies (the electroplating of metals and the large-scale production of aluminum
and chlorine).
Scientists make electrochemical measurements on chemical systems for a
variety of reasons. They may be interested in obtaining thermodynamic data about a
reaction. They may want to generate an unstable intermediate such as a radical ion and
study its rate of decay or its spectroscopic properties. They may seek to analyze a
solution for trace amounts of metal ions or organic species. In these examples,
electrochemical methods are employed as tools in the study of chemical systems in just
the way that spectroscopic methods are frequently applied. There are also
investigations in which the electrochemical properties of the systems themselves are of
primary interest, for example, in the design of a new power source for the
electrosynthesis of some product. Many electrochemical methods have been devised.
Their application requires an understanding of the fundamental principles of electrode
reactions and the electrical properties of electrode-solution interfaces.
(based on A.J. Bard et al. Electrochemical Methods)
Electrochemistry: The
Subject Matter
4 Divide into 4 groups and draw schematically the processes that take place in
the following areas related to electrochemistry.
Group 1 Group 2 Group 3
Electroplating of metals Generating an unstable
5 Match the verbs / verbal phrases and the prepositions they are used with. Find
them in the text from exercise 3 and translate the sentences into Russian. Then
make up sentences of your own using any 3 of them.
1) to deal a) in
2) to be caused b) with
3) analyze something c) as
4) to be interested d) with
5) to be employed e) for
6) to be concerned f) by
6 Match the terms and their definitions.
1) 1) indicator (n) a) A place where two things meet
2) 2) junction (n) b) A general truth or proposition.
3) fix (v) c) To answer with words or actions
4) respond (v) d) To find the answer to a mathematical problem
5) metal (n) e) Something that points out information.
6) principle (n) f) An action that is caused by another action.
7) require (v) g) A division of a book into a logical unit.
8) reaction (n) h) Important
9) chapter (n) i) An element that forms a base by combining
Electrochemistry: The
Related Phenomena
intermediate (radical ion)
Electrochemistry:
Practical Application
Analyzing a solution of
trace amounts of metal ions
70
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