1
Q
What should be noted when devising a reaction sequence in organic synthesis?
A
The difference in the number of carbon atoms between the starting compound and the compound required.
2
Q
What must be involved if there is a difference in the number of carbon atoms during synthesis?
A
One or more steps must involve a reaction where the length of the carbon chain is altered.
3
Q
What does the reaction of potassium cyanide with a halogenoalkane produce?
A
A nitrile.
4
Q
What can a nitrile be hydrolysed to produce?
A
A carboxylic acid.
5
Q
What reagent can reduce a nitrile to give an amine?
A
Lithium tetrahydridoaluminate(III).
6
Q
Fill in the blank: The reaction of potassium cyanide with 1-bromobutane produces _______.
A
pentylamine.
7
Q
What is the product of hydrolysing a nitrile?
A
A carboxylic acid.
8
Q
What is the final product of hydrolysing pentanenitrile?
A
Pentanoic acid.
9
Q
True or False: Potassium cyanide can react with a halogenoalkane to produce a nitrile.
A
True.
10
Q
Fill in the blank: The hydrolysis of a nitrile involves warming with _______.
A
dilute acid.
11
Q
What is one method of lengthening the carbon chain?
A
Addition of hydrogen cyanide to an aldehyde or ketone, followed by hydrolysis of the hydroxynitrile.
12
Q
What reaction can be used to introduce a carbon-containing side chain to a benzene ring?
A
Friedel-Crafts alkylation or acylation reaction.
13
Q
In a Friedel-Crafts acylation reaction, what is phenylethanone?
A
A product formed from the reaction.
14
Q
Fill in the blank: The reaction of hydrogen cyanide with an aldehyde or ketone results in a _______.
A
hydroxynitrile.
15
Q
True or False: Friedel-Crafts reactions can only be used for alkylation.
A
False.
16
Q
What is produced when heating an acid or its salt with soda lime?
A
An alkane that contains fewer carbon atoms than the starting material
This process involves a decarboxylation reaction.
17
Q
What does a flow chart of reactions help with?
A
Learning about reaction sequences
Flow charts visually represent the steps in chemical reactions.
18
Q
What is the role of KCN in the reaction sequence involving ethene?
A
It is used to convert ethene to CH3CH2CN
KCN acts as a nucleophile in the reaction.
19
Q
What reagent is used to convert CH3CH2CN to CH3CH2COOH?
A
H2SO4(aq)
This step involves hydrolysis of the nitrile.
20
Q
What is the product of the reaction between CH3CH2Br and NaOH(aq)?
A
CH3CH2OH
This reaction results in the formation of an alcohol.
21
Q
What is the result of the reaction of ethene with HBr?
A
CH3CH2Br
This is an example of an electrophilic addition reaction.
22
Q
What catalyst is used in the hydrogenation of ethene?
A
Pt/Ni
Platinum or nickel can act as a catalyst in this reaction.
23
Q
Fill in the blank: Heating an acid or its salt with soda lime leads to a _______.
A
decrease in chain length
24
Q
What is the starting material in the reaction sequence centered on ethene?
A
Ethene
Ethene is the foundational compound in this sequence of reactions.
25
What is the significance of essential conditions in reaction sequences?
They are omitted for clarity in flow charts
## Footnote
Essential conditions include temperature, pressure, and time.
26
What is an important part of any organic preparation?
The separation and purification of the products
## Footnote
This is crucial because many organic reactions do not go to completion and may produce multiple products.
27
What are the products when ethyl ethanoate is made from ethanol and ethanoic acid?
Ester, water, unreacted ethanol, unreacted ethanoic acid
## Footnote
The reaction can be represented as CH3CH2OH + CH3COOH → CH3COOCH2CH3 + H2O.
28
What is the outcome when the products are miscible liquids?
They can be separated using distillation
## Footnote
Distillation is effective when the boiling temperatures differ significantly.
29
When can simple distillation be used?
When the boiling temperature of the product differs by a reasonable amount (20°C or more) from other compounds
## Footnote
It can also separate a volatile liquid from non-volatile substances.
30
What happens if the product does not decompose at or below its boiling temperature?
Distillation can be used to separate the product
## Footnote
This technique is effective for non-decomposing products.
31
What types of mixtures may need different methods of separation?
Insoluble solids, solutions, immiscible liquids
## Footnote
Each type of mixture presents unique challenges for separation.
32
True or False: All reaction products are miscible with each other.
False
## Footnote
Some reactions produce products that may be insoluble or immiscible.
33
What is an example of distillation mentioned?
The distillation of 2-chloro-2-methylpropane from its mixture with 2-methylpropan-2-ol and hydrochloric acid
## Footnote
This illustrates a practical application of distillation in separating chemical compounds.
34
What are the boiling temperatures of the compounds mentioned?
* 82°C
* 51°C
* 100°C
## Footnote
These temperatures are relevant for understanding the distillation process.
35
What is used if the boiling temperatures are closer together?
Fractional distillation
## Footnote
Fractional distillation enhances the separation of components with close boiling points.
36
What equipment is used in fractional distillation?
A fractionating column
## Footnote
The fractionating column increases the efficiency of separation during distillation.
37
What is one application of fractional distillation mentioned?
The separation of ethanol obtained from the fermentation of sugars
## Footnote
This process highlights the importance of fractional distillation in producing ethanol.
38
What is another application of fractional distillation?
The primary separation of products present in crude oil (petroleum)
## Footnote
Fractional distillation is critical in the petroleum industry for separating various hydrocarbons.
39
What can be done for compounds that decompose at their boiling temperatures?
Distillation can be carried out under reduced pressures (vacuum distillation) or steam distillation
## Footnote
These techniques are used to prevent decomposition during the distillation process.
40
What is the purpose of reducing pressure in vacuum distillation?
To enable distillation for compounds that decompose just before or at their boiling temperatures
## Footnote
Lowering the pressure lowers the boiling point, allowing distillation at safer temperatures.
41
What is the effect of reduced pressure on boiling points?
Compounds boil at lower temperatures when distillation occurs at reduced pressure
## Footnote
For example, dodecane (C12H26) boils at 216°C under atmospheric pressure but at 92°C at 1.3 kPa.
42
What is steam distillation?
A method used to separate volatile compounds from a mixture by passing steam through it
## Footnote
It is particularly important in the perfumery industry.
43
Why is steam distillation used in the perfumery industry?
To extract essential oils from plants without decomposing them due to high temperatures
## Footnote
Essential oils may decompose if heated to their boiling temperatures at atmospheric pressure.
44
What happens to volatile compounds during steam distillation?
They pass over with steam and condense in the receiving flask
## Footnote
This process allows for the collection of essential oils.
45
What is one of the most widely used oils in the perfume industry?
Rose oil
## Footnote
It is extracted from rose petals through steam distillation.
46
What is produced from the steam distillation of rose petals?
An oil containing different compounds and water from condensed vapours
## Footnote
The oil is used in various fragrances and perfumes.
47
Fill in the blank: Steam is passed into the reaction mixture and the _______ compounds present pass over with the steam.
volatile
48
True or False: Steam distillation can be used to separate miscible liquids.
False
## Footnote
Steam distillation is used for separating immiscible liquids.
49
What is solvent extraction?
A method that depends on the differing solubility of a compound in two immiscible solvents.
50
How much more soluble is iodine in tetrachloromethane compared to water?
Iodine is about 90 times more soluble in tetrachloromethane than in water.
51
What happens when tetrachloromethane is added to an aqueous solution of iodine?
Most of the iodine is extracted into the tetrachloromethane layer.
52
What method is used to separate the two layers after solvent extraction?
Using a separating funnel.
53
What is the purpose of filtration in insoluble solid separation?
To separate a solid from the liquid present.
54
What equipment is typically used for filtration?
Filter paper and funnel.
55
What is the advantage of using fluted filter paper?
It is quicker than the traditional method.
56
What type of filtration can be done using a Buchner funnel?
Vacuum filtration.
57
What should be done to the solid in the funnel after filtration?
It needs to be washed with an appropriate solvent and dried.
58
At what temperature should the solid be dried?
At a temperature below its melting temperature.
59
Fill in the blank: Solvent extraction depends on the differing solubility of a compound in two _______ solvents.
[immiscible]
60
True or False: A fluted filter paper touches the funnel at all points.
False.
61
What is the first step in obtaining products from a solution containing a solute?
Crystallisation.
62
What is the purpose of using decolourising charcoal in a solution?
To remove color due to the presence of impurities.
63
How is decolourising charcoal used in the process?
The solution is boiled with decolourising charcoal and then filtered hot.
64
What should be done if no crystals appear when cooling the solution?
The solution needs to be made more concentrated.
65
What safety precautions should be taken when concentrating a flammable solvent?
Use a water bath or electrical heating method like a hot plate.
66
What is the process to obtain pure solute from crystallisation?
Recrystallisation.
67
List the essential steps for recrystallisation.
* Dissolve the solute in a minimum volume of hot solvent
* Filter hot, if necessary, to remove insoluble impurities
* Allow to cool
* Filter
* Wash the solid with a small amount of an appropriate solvent
* Dry at a temperature below its melting temperature.
68
True or False: The solute obtained by crystallisation is always pure.
False.
69
What is the first action taken when preparing for recrystallisation?
Dissolve the solute in a minimum volume of hot solvent.
70
Fill in the blank: The solution is boiled with a little decolourising charcoal to remove the _______.
colour.
71
What is polymerisation?
The joining together of a large number of monomer molecules.
72
What type of polymerisation do alkenes undergo?
Addition polymerisation.
73
What happens to the -C=C- double bond during addition polymerisation?
It is used to join the monomer units together, resulting in a polymer with only single bonds between carbon atoms.
74
What is an example of a monomer that undergoes addition polymerisation?
Propene.
75
What is the resulting polymer from propene called?
Poly(propene).
76
What characterizes condensation polymerisation?
The joining of monomer molecules with the loss of small molecules.
77
What small molecules are often lost during condensation polymerisation?
Water or hydrogen chloride.
78
What occurs when two different monomers with different functional groups are used in condensation polymerisation?
Small molecules are lost when bonding occurs between them.
79
Give an example of a condensation polymer formation.
A dicarboxylic acid bonds with a diol.
80
Fill in the blank: Condensation polymerisation occurs with the loss of _______.
small molecules.
81
True or False: Addition polymerisation results in polymers that contain double bonds.
False.
82
What type of polymerisation occurs between two different functional groups in one type of monomer molecule?
Condensation polymerisation
## Footnote
Example: Using an α,ω-amino acid with an amino group -NH and a carboxylic acid group -COOH
83
What is a characteristic of addition polymerisation?
No small molecule is lost and the polymer is the only product
## Footnote
This indicates that addition polymerisation results in a direct formation of a polymer without by-products.
84
What type of polymerisation occurs if the monomer is an alkene?
Addition polymerisation
85
What functional groups indicate that condensation polymerisation has occurred?
Functional groups such as -NH, -COOH, or -OH
## Footnote
These groups are typically involved in forming links through the loss of small molecules.
86
What type of link in a polymer chain indicates condensation polymerisation?
Amide link -C(O)N(H) or ester linkage -OC(O)-
87
What is a sign that addition polymerisation has occurred in a polymer chain?
The chain only consists of carbon atoms
88
What are polyesters used for?
Production of clothing, packaging, and plastic bottles.
89
What is the most common polyester?
PET (polyethylene terephthalate).
90
What are the necessary characteristics of monomers used to form polyesters?
They need to have a functional group at each end of the molecule.
91
What are the monomers used to produce PET?
* Ethane-1,2-diol
* Benzene-1,4-dicarboxylic acid (terephthalic acid).
92
True or False: Polyesters are only used in clothing production.
False.
93
What is PET used for?
Synthetic fibres such as Terylene, blankets, and filling material for duvets.
94
What is the biodegradability of PET?
PET does not easily biodegrade.
95
What is a polyester that can degrade quickly in landfill?
Poly(lactic acid), PLA.
96
What are the renewable resources from which PLA can be derived?
Corn starch or sugar cane.
97
What is the relationship between lactic acid and PLA?
PLA is made from the polymerisation of 2-hydroxypropanoic acid (lactic acid).
98
How many types of monomer molecules does PET require?
Two different types of monomer molecules.
99
What type of polymerisation do polyamides undergo?
Condensation polymerisation.
100
What was the first polyamide made and in what year?
Nylon 6,6, made in 1935.
101
What is the starting material for making Nylon 6,6?
Benzene.
102
What is the process of converting benzene to hexanedioic acid?
Benzene is reduced to cyclohexane, oxidised to cyclohexanol and cyclohexanone, and then oxidised to hexanedioic acid.
103
Fill in the blank: PLA is made from one type of _______ molecule.
[monomer]
104
True or False: PLA is a synthetic fibre.
False.
105
What is the product formed from hexanedioic acid and hexane-1,6-diamine?
Nylon 6,6
## Footnote
Named because each of the two monomers has six carbon atoms.
106
When was Nylon 6 developed?
1939
## Footnote
Developed in Germany.
107
What is Nylon 6 derived from?
6-aminohexanoic acid
## Footnote
Contains six carbon atoms.
108
Fill in the blank: Nylon 6,6 is formed from hexanedioic acid and _______.
hexane-1,6-diamine
109
True or False: Nylon 6,6 is named for having two monomers with eight carbon atoms each.
False
## Footnote
Each monomer has six carbon atoms.
110
What type of polymer is Nylon 6,6?
Polyamide
111
Fill in the blank: The reaction that forms Nylon 6,6 results in the release of _______.
water
112
What is the significance of the number 6 in Nylon 6,6?
It indicates the number of carbon atoms in each monomer.
113
What are the two primary components used to create Nylon 6,6?
Hexanedioic acid and hexane-1,6-diamine
114
What is Nylon 6 produced from?
Caprolactam
## Footnote
Caprolactam is made from benzene in several stages.
115
How is Nylon 6 created from caprolactam?
By treating caprolactam with water, which opens the ring and polymerises it.
116
What are the starting materials for producing Kevlar?
Benzene-1,4-dioic acid and benzene-1,4-diamine.
117
What are two notable properties of Kevlar?
Good fire retardant properties and five times stronger than steel.
118
What application is Kevlar commonly used for?
Bullet proof vests.
119
Fill in the blank: Kevlar can be produced from _______.
Benzene-1,4-dioic acid and benzene-1,4-diamine.
120
True or False: Nylon 6 is produced directly from benzene.
False.
121
What process leads to the formation of Nylon 6 from caprolactam?
Polymerisation after ring opening.
122
What is the strength comparison of Kevlar to steel?
Five times stronger than steel.
123
Fill in the blank: Kevlar is known for its good _______ properties.
Fire retardant.
124
What is the melting temperature of a solid?
The temperature at which the solid begins to change into a liquid
125
How does the melting temperature help in identifying pure substances?
It occurs at a sharp temperature (within 1°C) for many pure substances
126
What effect do impurities have on the melting temperature?
They lower the expected melting temperature and cause the compound to melt over a range of temperatures
127
What happens if a sample of a compound has a sharp melting temperature of 122°C and is mixed with pure benzenecarboxylic acid?
If the melting temperature remains the same, the compound is likely benzenecarboxylic acid; if it lowers and is not sharp, it is not
128
What types of substances are often difficult to obtain accurate melting temperatures for?
Aldehydes and ketones
129
What is the purpose of reacting an aldehyde or ketone with 2,4-dinitrophenylhydrazine?
To give a derivative that is easier to measure the melting temperature
130
What is a characteristic of 2,4-dinitrophenylhydrazones?
They are usually orange-red solids
131
How can the melting temperature of a 2,4-dinitrophenylhydrazone be used?
It can be compared with a table of melting temperatures to identify the starting aldehyde or ketone
132
What method is usually used to find the melting temperature of a compound?
An electrical heating method
133
What is a method to find the melting temperature?
Heating bath method
## Footnote
This method involves using a heating bath to determine the melting temperature of a sample.
134
What equipment is used to hold the sample during melting point determination?
Capillary tube
## Footnote
A capillary tube is used to contain the sample during the melting temperature measurement.
135
What is the depth of the sample typically placed in the capillary tube?
2-3 mm
## Footnote
This depth is recommended for accurate melting temperature determination.
136
What is used to attach the thermometer to the capillary tube?
Rubber band
## Footnote
A rubber band is used to secure the thermometer to the capillary tube.
137
What type of liquid is used in the heating bath for melting temperatures below 100°C?
Water
## Footnote
Water is suitable for samples with melting temperatures likely below 100°C.
138
What type of liquid is used in the heating bath for melting temperatures above 100°C?
Silicone oil or other non-flammable liquid
## Footnote
Silicone oil is preferred for higher melting temperatures to ensure safety.
139
What is the purpose of gently heating and stirring the mixture?
To determine the melting temperature
## Footnote
Gentle heating and stirring help achieve a uniform temperature for accurate measurement.
140
What is the main application of low-resolution proton magnetic resonance spectroscopy (*H NMR)?
Identification of chemical structures
## Footnote
*H NMR is particularly useful for determining the structure of organic molecules.
141
What is the structure of ethane?
H-C—C-H
## Footnote
Ethane has a simple linear structure with all hydrogen protons in equivalent environments.
142
How many signals are observed in the NMR spectrum of ethane?
One signal
## Footnote
All hydrogen protons in ethane are equivalent, resulting in a single peak.
143
What happens to the hydrogen atoms in chloroethane compared to ethane?
One hydrogen is replaced by a chlorine atom
## Footnote
This substitution changes the environment of the hydrogen atoms.
144
How many different environments do the hydrogen atoms occupy in chloroethane?
Two environments
## Footnote
In chloroethane, the three CH3 protons are identical and the two CH2 protons are in a different environment.
145
What does the NMR spectrum of chloroethane show?
Two peaks with peak areas of 3:2
## Footnote
The peak areas represent the number of protons in each type of hydrogen environment.
146
Fill in the blank: In chloroethane, the CH3 protons are in _______ environments.
identical
## Footnote
The three CH3 protons are in the same environment.
147
Fill in the blank: The two CH2 protons in chloroethane are in a _______ environment.
different
## Footnote
This difference leads to the appearance of two distinct peaks in the NMR spectrum.
148
What is the chemical structure of 1,2-dichloroethane?
CI - C - Cl
## Footnote
In this structure, all hydrogen protons are in an identical environment.
149
How many different environments do the hydrogen protons in 1,1-dichloroethane have?
Two different environments
## Footnote
This leads to multiple signals in the NMR spectrum.
150
True or False: The 1H NMR spectrum of 1,1-dichloroethane shows only one signal.
False
## Footnote
There are two signals due to different environments of hydrogen protons.
151
Fill in the blank: The peak in the 1H NMR spectrum for the CHCl hydrogen proton in 1,1-dichloroethane is seen at _______.
5.98
## Footnote
This peak indicates the presence of the CHCl proton in a distinct environment.
152
Fill in the blank: In 1,2-dichloroethane, all hydrogen protons are in an _______ environment.
identical
## Footnote
This leads to a single peak in its NMR spectrum.
153
What causes the splitting of peaks in the H NMR spectrum of 1,1-dichloroethane?
The magnetic environment of a proton or protons in one group is affected by the magnetic environment of neighbouring groups.
154
What is the term used for the process of signal splitting in NMR spectroscopy?
Spin-spin coupling.
155
In the high resolution 1H NMR spectrum of 1,1-dichloroethane, how many peaks does one signal split into?
Four peaks (a quartet).
156
In the high resolution 1H NMR spectrum of 1,1-dichloroethane, how many peaks does the other signal split into?
Two peaks (a doublet).
157
Which neighboring atoms usually affect the hydrogen protons in spin-spin coupling?
* Carbon
* Nitrogen
* Oxygen
158
Why do the hydrogen atoms in 1,1,2,2-tetrachloropropane show no splitting in the high resolution 1H NMR spectrum?
The hydrogen atoms are not bonded to adjacent carbon atoms.
159
What is the range of m/z signals observed in the mass spectrum of 1,1,1,2-tetrachloropropane?
The signals range from m/z 328.
160
How many signals does the 1H NMR spectrum of 1,1,1,2-tetrachloropropane show?
Three signals.
161
What type of compound is represented by the formula C-OR in the context of NMR?
An ester of a dicarboxylic acid.
162
Fill in the blank: The formula shown below represents an _______ of a dicarboxylic acid.
ester
163
What happens to the single peak of a hydrogen proton bonded to a carbon, nitrogen, or oxygen atom when it has n hydrogen protons bonded to an adjacent atom?
It will be split into (n + 1) smaller peaks.
164
In 'H NMR spectra, what does the peak height indicate?
It gives information about the number of protons.
165
In 13C NMR spectra, does the peak height provide information?
No, it does not provide any information.
166
What type of spectrum can be used alongside 13C NMR and 'H NMR spectra to find the structure of a compound?
Mass spectrum and infrared absorption spectrum.
167
True or False: The splitting pattern in NMR spectroscopy is influenced by adjacent hydrogen atoms.
True
168
Fill in the blank: A hydrogen proton bonded to an adjacent atom will have its single peak split into _______ smaller peaks if there are n hydrogen protons bonded to that adjacent atom.
(n + 1)
169
What relative peak pattern is observed in a compound with hydrogen(s) that results in a triplet?
It indicates the presence of adjacent hydrogen(s) affecting the splitting.
170
What type of NMR spectrum is used to analyze carbon atoms in a compound?
13C NMR spectrum.
171
What is the significance of the peak area in NMR spectroscopy?
It indicates the relative number of protons contributing to that peak.
172
Fill in the blank: In 'H NMR spectra, the peak height indicates the number of _______.
protons.
173
What is chromatography?
A technique used to separate substances from a mixture by their slow movement through or over a stationary phase.
174
When was chromatography developed?
Early in the 20th century.
175
What was the initial use of chromatography?
To separate plant pigments using a column containing powdered calcium carbonate.
176
What has chromatography been extensively developed for?
To separate mixtures of substances using different methods appropriate to the components present.
177
What type of method was chromatography originally considered?
Qualitative method.
178
Can chromatography be used quantitatively?
Yes, it can now be used in a quantitative way.
179
What is chromatography often used in conjunction with?
Mass spectrometry.
180
What is the emphasis of the topic discussed?
Finding the composition of mixtures.
181
Is a description of the mechanisms for the separation process required?
No, it is not required.
182
Fill in the blank: Chromatography separates substances based on their _______ movement through or over a stationary phase.
[slow]
183
What is the stationary phase in paper chromatography?
Water trapped in the cellulose fibres of the paper
## Footnote
This phase allows for the separation of components based on their affinity to the stationary phase.
184
What is the stationary phase in Thin Layer Chromatography (TLC)?
A layer of silica (SiO2) or aluminium oxide (Al2O3) coated onto a plastic or glass plate
## Footnote
TLC uses these materials for better separation efficiency.
185
What are the initial steps in both paper chromatography and TLC?
Spots of the starting materials are placed at the bottom of the chromatography paper or TLC plate
## Footnote
This is followed by placing the paper/plate in a suitable solvent.
186
What happens to the solvent front in chromatography?
It rises up the paper/plate, separating the mixture into a series of spots
## Footnote
The movement of the solvent front is crucial for the separation process.
187
What is measured after the chromatography process is completed?
The position of the separated spots and the solvent front
## Footnote
This data is essential for calculating Rf values.
188
What does Rf stand for in chromatography?
Retention factor
## Footnote
It quantifies the distance a compound travels relative to the solvent front.
189
How is the Rf value calculated?
Rf = distance moved by spot (X) / distance moved by the solvent front (Y)
## Footnote
This formula helps in identifying compounds based on their movement.
190
True or False: The techniques for paper chromatography and TLC are different.
False
## Footnote
Both methods share similar techniques but differ in the stationary phase.
191
What is compared to determine if an unknown solute matches a known solute?
The position of the spots for a known and the unknown solute
## Footnote
This comparison helps in identifying unknown substances.
192
What is the technique called when a dried chromatogram is rotated 90° and a different solvent is used?
Two-way separation
## Footnote
This technique helps to overcome incomplete separation of spots.
193
What does the solvent front indicate in chromatography?
The leading edge of the solvent in the chromatographic process
## Footnote
It marks the distance traveled by the solvent on the chromatogram.
194
Fill in the blank: The process of rotating the dried chromatogram is done by _______.
90°
195
What is the purpose of using a different solvent in two-way separation?
To enhance the separation of spots that did not completely separate with the first solvent
## Footnote
This technique improves resolution in chromatographic analysis.
196
True or False: Two-way separation is only performed with the same solvent.
False
197
What is the start line in chromatography?
The initial line where the sample is applied before the solvent moves
## Footnote
It serves as a reference point for measuring the distance traveled by the solvent and the spots.
198
What is the purpose of spraying a chromatogram with a suitable reagent?
To cause colorless spots to become colored
## Footnote
An example is spraying with ninhydrin to visualize amino acids.
199
What color do amino acids turn when ninhydrin is applied to a chromatogram?
Blue-purple
## Footnote
This indicates the position of different amino acids on the chromatogram.
200
How can the position of colorless spots be visualized using UV light?
Fluorescent compounds show a color or the plate has a fluorescent coating
## Footnote
Dark spots appear on a fluorescent background.
201
What are two advantages of TLC over paper chromatography?
* Faster
* Variety of materials for thin layer
## Footnote
TLC is widely used in forensic science.
202
What is the most common type of gas chromatography?
Gas-liquid chromatography (GLC)
## Footnote
It involves passing a gaseous mixture through liquid particles on an inert solid.
203
What role does the carrier gas play in gas chromatography?
Sweeps the gaseous mixture into the column
## Footnote
Common carrier gases include hydrogen, helium, or argon.
204
What factors influence the efficient separation of compounds in GLC?
* Volatility of the compound
* Column temperature
* Length of the column
* Flow rate of the carrier gas
## Footnote
Boiling temperatures are also important for similar compounds.
205
What is retention time in gas chromatography?
The time taken from the sample entering the injection port until it reaches the detector
## Footnote
Retention times vary based on several factors.
206
What is the significance of retention time for identification in GLC?
It depends on the conditions being exactly the same
## Footnote
Variability can lead to different retention times.
207
What technique is abbreviated as GC-MS?
Gas chromatography-mass spectrometry
## Footnote
It is used for positive identification of separated components.
208
What does the ABE fermentation process produce?
* Propanone (acetone)
* Butan-1-ol
* Ethanol
## Footnote
It utilizes starch as a starting material.
209
What is shown in a typical GC chromatogram from the ABE process?
The products of the fermentation process
## Footnote
This illustrates the separation and identification of fermentation products.
210
What is the purpose of spraying a chromatogram with a suitable reagent?
To cause colorless spots to become colored
## Footnote
An example is spraying with ninhydrin to visualize amino acids.
211
What color do amino acids turn when ninhydrin is applied to a chromatogram?
Blue-purple
## Footnote
This indicates the position of different amino acids on the chromatogram.
212
How can the position of colorless spots be visualized using UV light?
Fluorescent compounds show a color or the plate has a fluorescent coating
## Footnote
Dark spots appear on a fluorescent background.
213
What are two advantages of TLC over paper chromatography?
* Faster
* Variety of materials for thin layer
## Footnote
TLC is widely used in forensic science.
214
What is the most common type of gas chromatography?
Gas-liquid chromatography (GLC)
## Footnote
It involves passing a gaseous mixture through liquid particles on an inert solid.
215
What role does the carrier gas play in gas chromatography?
Sweeps the gaseous mixture into the column
## Footnote
Common carrier gases include hydrogen, helium, or argon.
216
What factors influence the efficient separation of compounds in GLC?
* Volatility of the compound
* Column temperature
* Length of the column
* Flow rate of the carrier gas
## Footnote
Boiling temperatures are also important for similar compounds.
217
What is retention time in gas chromatography?
The time taken from the sample entering the injection port until it reaches the detector
## Footnote
Retention times vary based on several factors.
218
What is the significance of retention time for identification in GLC?
It depends on the conditions being exactly the same
## Footnote
Variability can lead to different retention times.
219
What technique is abbreviated as GC-MS?
Gas chromatography-mass spectrometry
## Footnote
It is used for positive identification of separated components.
220
What does the ABE fermentation process produce?
* Propanone (acetone)
* Butan-1-ol
* Ethanol
## Footnote
It utilizes starch as a starting material.
221
What is shown in a typical GC chromatogram from the ABE process?
The products of the fermentation process
## Footnote
This illustrates the separation and identification of fermentation products.
222
What does HPLC stand for?
High performance liquid chromatography
223
What is the main purpose of HPLC?
Separation of compounds that vaporise at high temperatures
224
What is the process involved in HPLC?
A mixture sample is dissolved in a solvent and forced through a packed column at high pressure
225
What are the applications of HPLC?
* Testing urine samples for banned substances
* Food chemistry for detecting antioxidants
226
What are common antioxidants detected by HPLC?
* BHA
* BHT
* Various esters of gallic acid
227
Fill in the blank: BHA can have the C(CH3)3 group in the _______ positions in the ring.
2- or 5-
228
True or False: HPLC can be used for compounds that decompose at high temperatures.
False
229
What is a specific application of HPLC in food chemistry?
Detecting the presence of antioxidants in fatty food products
230
What is the role of antioxidants in food chemistry?
Prevent oxidation in food products such as margarine and cream cheese
231
What is the structural formula for BHA?
C(CH3)3 group with a hydroxyl group
232
What is the significance of retention time in HPLC?
It helps in identifying and quantifying compounds in a mixture
233
Fill in the blank: High performance liquid chromatography was previously known as _______.
high-pressure liquid chromatography
234
What type of samples can HPLC analyze?
Mixtures that include compounds that do not vaporize easily
