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Файл:English in Analytical Chemistry communicating about Methods & Techniques. Учебное пособие. Книга для студента
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Indicators’ List
1) litmus;
2) phenolphthalein;
3) thymol blue;
4) methyl orange;
5) methyl yellow;
6) methyl red;
7) bromocresol green;
8) phenol red;
9) alizarin;
10) cresol red;
11) bromophenol blue;
12) indigo carmine;
13) malachite green;
14) congo red.
22 Work in teams and do the following quiz on analytical indicators. Choose one
of the options by casting lots. Certain points must have been mentioned in your
groupmates’ presentations, and some of them might require a web search of your
own.
Option 1
Let’s list all the indicators first: eriochrome black T, xylenol orange, congo red,
alizarin, methyl yellow
1. This indicator can be used to analyze water hardness.
2. This indicator has a formula C14H8O4 and is extracted from madder.
3. This indicator is used to detect rare earth metals and transition metals.
4. This indicator was developed in Germany and is used to detect nitrates.
5. This indicator was developed in London by Peter Griess and could be
hazardous for your health if used is a dye.
6. This indicator is applied in back or displacement complexation titration.
7. This indicator could be used for the analysis in the presence of ultraviolet
light.
8. This indicator has color transitions from pitch blue to red and orange.
9. This indicator was used as paint by one of the famous Dutch artists.
Option 2
Let’s list all the indicators first: methylthymol blue, azo violet, malachite green,
Rhodamine C
1. This indicator is normally NOT used in basic medium.
2. This indicator is used for acid base titration and for qualitative analysis.
3. This indicator is purple crystalline powder used to detect metals.
4. This indicator is applied in precipitation titration.
5. This indicator contains a group of two nitrogens linked together with a
double bond.
6. This indicator is applied as a dye or a biological stain.
7. In the presence of magnesium salts, it transforms to deep blue.
8. This indicator exists in the form of oxalate.
9. This indicator has glowing properties.
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1. Let’s list all the indicators first: indigo carmine, congo red, phenol red,
alizarin, cresol red, methyl red
2. This indicator is applied in redox and acid base titration, in food industry,
and in the production of ink.
3. This indicator was discovered by two scientists from Germany and
developed by an English biochemist.
4. This indicator is component of many mixed (=complex) indicators.
5. This indicator’s name is connected with colonization of Africa.
6. This indicator is a bright red dye used to fix the colour (=mordant dye).
7. This indicator has a colour transition from red to yellow, but in nature it is
dark red or glittering green.
8. This indicator is used to test home swimming pools and the kidney
function.
9. This indicator is used for color markers.
Let’s list all the indicators first: phenolphthalein, alizarin, litmus, thymol blue,
bromocresol green, methyl orange, bromophenol blue
1. This indicator was discovered by Adolf Beyer and can be applied for acid
base titration.
2. This indicator was discovered by a Spanish scientist.
3. Color transition for this indicator varies between yellow and blue.
4. In AC, this indicator is applied to detect aluminium.
5. This indicator has color in basic medium only.
6. This indicator has a formula C14H8O4 and is extracted from madder
plant.
7. This indicator is insoluble in water.
8. This indicator is yellow in acidic medium and blue in basic medium.
9. The color transition for this indicator is from red to yellow to blue.
10. In the pH range less than 5, the color transition varies from red to green.
11. This indicator is applied as a dye or a biological stain.
12. This indicator is applied to detect oxidizing agents; its colour transition is
from red to orange yellow.
Let’s list all the indicators first: litmus, alizarin, congo red, methyl yellow,
methyl red
1. It is one of the most popular acid base indicators.
2. This indicator contains a group of two nitrogens linked together with a
double bond.
3. This indicator was discovered by a Spanish scientist.
4. This indicator’s name is connected with colonization of Africa by Germany.
5. In color transition of this indicator, the colours of dark pink and purple are
present.
6. This indicator is produced from a primitive plant.
7. This indicator is insoluble in water, but soluble in alcohol.
8. This indicator was developed in Germany and is used to detect nitrates.
9. This indicator is suitable for a titration of Lewis acid.
10. This indicator is used to titrate sodium carbonate with sulfuric acid.
11. In AC, this indicator is applied to detect aluminium ions.
12. This indicator was developed in London by Peter Griess and could be
hazardous for your health if used is a food additive (butter, margarine…).
Option 3
Option 4
Option 5
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Let’s list all the indicators first: phenolphthalein, methyl orange, malachite
green, indigo carmine
1. This indicator is used in forensic chemistry for the detection of latent
blood.
2. This indicator was developed by 3 scientists at once.
3. This indicator is soluble in ethers and alcohols; it is colorless and
tasteless, but has a specific smell.
4. This indicator was discovered by Adolf Beyer and can be applied for acid
base titration.
5. This indicator has color in basic medium only.
6. The name of this indicator is associated with a name of the flower.
7. This indicator is applied in redox and acid base titration, in food industry,
and in the production of ink (чернила).
8. This indicator has a specific colorless form.
9. The name of this indicator in connected with an Asian country.
10. The color transition for this indicator varies from blue to yellow.
11. This indicator has one drawback: it has similar colors in different media.
Let’s list all the indicators first: litmus, phenolphthalein, methyl red, malachite
green, congo red, alizarin
1. This indicator was discovered by a Spanish scientist.
2. This indicator was developed in Germany.
3. This indicator is used for acid base titration; its color transition is from dark
pink to purple.
4. This indicator is in the orange crystalline form and is hard to apply in the
industry.
5. This indicator is used to identify bacteria; its color transition varies
between red and yellow.
6. This indicator is applied for the titration of weak organic acids.
7. This indicator has two main components: azolitmin and erythrolitmin.
8. This indicator is used for purifying aquariums.
9. This indicator has color in basic medium only.
10. It is a dark powder with a smell of ammonia.
11. This indicator was synthesized by two scientists.
12.
Let’s list all the indicators first: alizarin, methyl yellow, litmus, methyl orange,
bromocresol green
1. This indicator was used by an alchemist.
2. This indicator is used as a dye.
3. This indicator is insoluble in water and soluble in alcohols.
4. In AC, this indicator is applied to detect aluminium ions.
5. This indicator was discovered in 17
continued in Russia.
6. This indicator was discovered by Liberman and Grebe.
7. This indicator is synthesized by the bromination of cresol and is applied as
a food and drug colorant.
8. This indicator is obtained from natural materials (plant of blue lichens).
9. This indicator is used for colorimetric analysis.
Option 6
Option 7
Option 8
th
century in Germany. Its history
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Further Watching and Speaking
23 Watch the second part of the video on titrimetric procedure and answer the
questions. Follow the link: https://disk.yandex.ru/i/_64vaDcSwM8qDQ
Titration Calculations
1. What are the substances used for titration?
2. What do they begin with?
3. What is the indicator used? What are its colors?
4. What is the volume of titrant?
5. What are the initial and the final values?
6. What for do we need to record the final volume and subtract the initial volume?
7. Record the number of moles for sulfuric acid.
24 Re-watch the video and fill in the gaps in the script below. Then, state the
questions to the underlined word combinations or make up a sentence using one
of these combinations.
Hi! I'm Jared Heymann, an Assistant Professor of Chemistry at Elon University.
Today, we'll be [...].
In part 1 of this video series we discussed the proper [...] for [...], reading, and
using a burette. In this video, we take it a step [...] and [...] of an unknown solution of [...]
by titrating with a [...] of known concentration.
All titrations begin with a [...] chemical equation. In our case one mole of [...] is
[...] with two moles of [...] – our base. Phenolphthalein is the [...] indicator for this
reaction. It is [...] in [...] solutions and [...] in basic solutions.
Typically, titrations are performed [...]. Use an average volume of the titrant
required to reach the endpoint for any calculations. Perform an estimate titration. [...]
your final volume, [...] your initial volume, and determine the number of added mL of
base. In our reaction we use the [...] point 0.002 molar solution of sodium hydroxide.
Knowing now that it takes [...], we can [...] the number of moles of sodium
hydroxide it took to neutralize our 10 mL of H2SO4. Now that we've calculated the
number of moles of sodium hydroxide, we can recall from our [...] equations that for
every two moles of sodium hydroxide one mole of sulfuric acid is neutralized. Therefore,
we can calculate the number of moles of sulfuric acid. The titration [...] 10 mL of H2SO4.
Divide it into the calculated number of moles. For this trial, the [...] of sulfuric acid is [...]
molar.
Carolina has everything you need for your chemistry lab. Visit us at Carolina
Chemistry dot com to see our titration [...] for chemistry.
(Based on carolinachemistry.com free videos)
25 Watch the video ‘Introduction to Titrations’ and answer the questions below.
Follow the link: https://disk.yandex.ru/i/EC-YpRjV9vpfzA
1. Which solutions are used in titration and what for?
2. List 5 characteristics of water solutions that make them helpful in titration.
Define them.
3. What is the main characteristic provided for acid-base titration?
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4. What is the main characteristic provided for oxidation-reduction titration?
5. What is the main characteristic provided for precipitation titration?
6. What is the main characteristic provided for conductimetric titration?
7. Formulate the requirement for the indicators used in acid-base titration.
8. Pause the video at 4:08, solve the problem, discuss it, and then play again to
check the answer. Then try to reproduce the author’s solution by pausing the
video and speaking after him.
9. Explain the mechanism of indicators.
10. How does methyl orange work in the example given?
26 Prepare for the generalizing seminar on gravimetric and titrimetric methods.
Questions Suggested
1 Present the core vocabulary items in gravimetry and explain them. Provide
contextual examples.
2 List the main equipment items and reagents needed for gravimetric analysis.
Describe their functions.
3 Present the basic facts about gravimetry. Provide examples.
4 Present the step-by-step procedure for gravimetric determination of iron (or any
other procedure).
5 Speak on the main types of gravimetry. State the procedure.
6 Present the core vocabulary items in titrimetry and explain them. Provide
contextual examples.
7 List the main equipment items needed for titrimetric analysis. Describe their
functions.
8 Present the main facts about titrimetry. Provide examples.
9 Present the step-by-step procedure for titration. Mention the calculations briefly.
10 Speak on one of the indicators used in titrimetry. Mention its history, practical
application. If possible, describe your personal experience in applying this
indicator.
11. Speak on the main types of titrimetry. Provide their crucial characteristics.
Writing
27 Study the information below and write down your own lab report.
Introduction to the Formal Laboratory Report
Titration Lab Guidelines
Explanation:
Lab reports are the most important kind of document written by students in science and
engineering programs at the university level. Regardless of the experiment performed,
the goal of a lab reports is always the same: to document your findings and
communicate what it means.
A good lab report does more than present data; it demonstrates the writer's
understanding of the concepts behind the experiment. Merely recording the expected
and observed results is not enough; you should also identify how and why differences
occurred, and show your understanding of the principles the experiment was created to
study.
A lab report should contain the following:
1. Title page: containing the title of the experiment, your name, the name of the lab
partners, the date, the teacher's name and the class
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2. Introduction: The introduction states the purpose of the experiment and also
"
provides the reader with any background and theory relevant to the lab.
Sample Introduction for a Flame Test lab
By placing atoms of a metal into a flame, electrons can be induced to absorb energy
and jump to an excited energy state, a quantum jump. They then return to their ground
state by emitting a photon of light (the law of conservation of energy indicates that the
photon emitted will contain the same amount of energy as that absorbed in the quantum
jump). The amount of energy in the photon determines its color; red for the lowest
energy visible light, increasing energy through the rainbow of orange yellow green blue
indigo, and finally violet for the highest energy visible light.
In this lab record the flame test color of several metals by capturing droplets of solutions
of salts, or ionic compounds of those metals with a platinum wire loop, then placing the
loop into a bunsen burner flame. Record the colors of light observed and compare this
data to the known electron arrangements for each metal tested.
3. Materials: list all chemicals and equipment used in the experiment.
4. Procedure: describes the process in chronological order. Using clear paragraph
structure, explain all steps in the experiment. A diagram is often helpful to illustrate
apparatus or techniques. Be sure to include sufficient detail, for example:
"Hydrochloric acid was reacted with sodium hydrogen carbonate.
"5.05 g of NaHCO3 was weighed into an evaporating dish. Approximately 6 ml
of 6M HCl was obtained in a small beaker. The HCl was then added to the
NaHCO3 slowly using an eye dropper until the reaction appeared to be
complete (no more bubbles were visible)."
NOT enough detail
Enough detail
Hint. If you are wondering if your procedure includes enough detail, ask yourself this,
"Would another student be able to read it and duplicate what you have done?"
5. Data/Results: This is where you record what happened in the lab. Results include all
measurements, data tables, calculations and graphs. Any formulas should be written
out before data is plugged in.
6. Discussion: The discussion is the most important part of your report, because here,
you show that you understand the theory behind the procedure. The following issues
should be discussed:
• Compare actual results with expected results.
• Analyze experimental error to account for differences in results. If the flaws result
from the experimental design, explain how the design might be improved. Avoid
statements such as ‘Human error was an issue, results could be improved by
being more careful.'
• Explain your results in terms of background theory. Labs are intended to illustrate
important laws, such as the Law of Conservation of Matter. Discuss how well the
lab results illustrate this theory.
7. Conclusion: One or two sentences that state exactly what was found in the
experiment.
8. References: Cite any sources of information you used in writing the report.
Voice/Tense: The entire report should be written in third person, past-tense, although
future tense is acceptable in the introduction section. For example, when writing the
procedure, instead of writing, "I will add 150 ml of HCl to a beaker” you should write, " A
46
beaker was obtained and 150 ml of HCl was added.” This is referred to as impersonal
(passive) writing, which is always to be used in scientific documents. It is
recommended that you avoid all personal pronouns (I, we, etc.)!
Check Yourself
1 Label the pictures.
1 2 3
4 5 6
7 8 9
10 11
2 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. Then make
up 10 questions to the text in exercise 1 above and ask your group as a teaching
assistant.
47
In a 12_______ method of analysis the volume of titrant reacting
stoichiometrically with the analyte provides 13 _______ information
about the amount of analyte in a sample. The volume of titrant
required to achieve this stoichiometric reaction is called the
14______ point. Experimentally we determine the titration's end
point using a visual indicator that 15_________ color near the
equivalence point. Alternatively, we can locate the end point by
recording a titration curve showing the titration reaction's progress
as a function of the titrant's volume. In either case, the end point
must 16______ match the equivalence point if a titration is to be
accurate. Knowing the shape of a titration curve is critical to
evaluating the feasibility of a proposed titri metric method.
Many titrations are direct, in which the titrant reacts with the
analyte. Other titration strategies may be used when a direct
17_______ between the analyte and titrant is not feasible. In a
back titration a reagent is added in excess to a solution containing
the analyte. When the reaction between the reagent and the
analyte is complete, the amount of excess reagent is 18________
titrimetrically.
In a displacement titration the analyte 19_____ a reagent, usually
from a complex, and the amount of the displaced reagent is
determined by an appropriate titration.
Titrimetric methods have been developed using acid-base,
complexation, redox, and precipitation reactions. Acid-base
titrations use a 20__________ acid or strong base as a titrant. The
most common titrant for a complexation titration is EDTA. Because
of their 21_____ against air oxidation, most redox titrations use an
oxidizing agent as a titrant. Titrations with reducing agents also are
possible. Precipitation titrations usually involve Ag+ as either the
analyte or titrant.
TITRANT
QUANTITY
EQUAL
CHANGE
CLOSE
REACT
DETERMINE
PLACE
STRENGTH
STABLE
3 Match the words with their definitions.
22 Titrant A empirical reflection of equivalence point
23 Titrimetry (titrimetric
method)
24 Titre C one of analytical methods that lies in determination of
25 Titrand (=titrated
analyte)
26 To titrate E solution with the known concentration applied to
27 Signal F to conduct the process of titration
28 Back titration G ratio of a solute mass to a solution volume expressed
29 Displacement titration H for this technique, one needs to add excessive solution
30 Direct titration I any kind of visible / observable change that we use for
31 Titration curve J one needs the supplementary reagent for this
B occurs because of the difference between equivalence
point and end point
an analyte quantity via alteration of a titrant volume.
D the solution / the soluble substance with unknown
concentration
determine the volume, hence, we can calculate
concentration or mass of a titrated analyte.
via mL
with definite concentration and we titrate the residual
titrant with another solution
analysis
48
technique
32 Equivalence point K graphically expressed dependence (=function) of pH to
a titrant volume (in acid base titration)
33 End point L the point on titration curve where the quantity of titrant
equals the quantity of a titrated analyte
34 Titration error M for this technique, only titrant is required
28-34 Excellent. You can use the vocabulary from Unit 2 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 Unit 2 and do the tasks again.
49
\
Unit 3
CHROMATOGRAPHY AND ELECTROPHORESIS
Learning objectives
In Unit 3, you will learn to describe and explain the general principle and
overall procedure of chromatography and electrophoresis as well as learn
the basics of chromatography types’ classification.
Chromatography was first devised in Russia by the
Italian-born scientist Mikhail Tsvet in 1900. He coined
the term chromatography and developed the technique
in the first decade of the 20th century, primarily for the
separation of plant pigments such as chlorophyll,
carotenes, and xanthophylls. Because these
components separate in bands of different colors (green,
orange, and yellow, respectively), they directly inspired
the name of the technique. New types of
chromatography developed during the 1930s and 1940s
made the technique useful for many separation
processes.
Mikhail Tsvet
Warming up
1 Watch a funny video on paper chromatography and answer the questions.
Follow the link: https://disk.yandex.ru/i/e_F2MZ31lg-kTQ
1. What is the purpose of paper chromatography?
2. Who are the main characters in the paper chromatography roleplay?
3. What are their functions?
4. What happens step by step?
5. What is the theoretical principle mentioned in the video?
Paper Chromatography
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