NATIONAL QUALIFICATIONS CURRICULUM SUPPORT
Chemistry
Consumer Chemistry
Predicting Physical Properties of
Molecules from Functional Groups
[HIGHER]
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Acknowledgement
Learning and Teaching Scotland gratefully acknowledges this contribution to the National
Qualifications support programme for Chemistry.
© Learning and Teaching Scotland 2010
This resource may be reproduced in whole or in part for educational purposes by educational
establishments in Scotland provided that no profit accrues at any stage.
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Contents
Introduction
4
Questions
5
Answers
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3
INTRODUCTION
Introduction
This resource supports the Consumer Chemistry unit of the revised Higher
Chemistry. The resource has the following purposes:
1.
to allow students to become familiar with identifying functional groups
within everyday molecules, some of which have complex structures
2.
to enable students to relate intermolecular forces to the functional
groups present
3.
to enable students to explain the physical properties of molecules based
on the functional groups present.
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QUESTIONS
Questions
Question 1
Benzaldehyde is an aromatic compound with an almond -like smell, which is
used in flavourings and perfumes.
Circle and name the functional group on the benzaldehyde molecule below.
O
C
H
Benzaldehyde
CONSUMER CHEMISTRY (H, CHEMISTRY)
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5
QUESTIONS
Question 2
Cholesterol is an important molecule present in the human body. However,
high levels of a certain type of cholesterol in the blood are linked with
illnesses such as heart disease and strokes.
CH2
HO
CH2
CH
CH3
C
CH2
CH2
CH2
CH
C
CH3
C
CH
CH3
CH
CH
CH3
CH2
CH2
CH2
CH
CH2
CH
CH2
CH2
Cholesterol
(a)
Identify the two circled functional groups on the cholesterol molecule .
(b)
Explain why this compound has a high boiling point.
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CH2
CH3
QUESTIONS
Question 3
β-carotene is a member of a family of chemicals called the carotenoids. It is responsible for the orange colour in many fruits
and vegetables, including carrots.
CH3
CH3
CH3
CH2 C
CH2
C
CH2 C
CH
CH
C
CH3
CH
CH
CH
C
CH3 C
CH
CH
CH
CH3
CH3
CH
C
CH
CH3
-carotene
(a)
Which functional group is present throughout the structure of β-carotene?
(b)
Is the carbon-to-carbon double bond polar or non-polar?
(c)
Which type of intermolecular forces will exist between β -carotene molecules?
CH
CH
C
CH3
CH
CH
C
CH2
CH2
C
CH2
CH3
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7
QUESTIONS
Question 4
The vanilla bean produces a compound called vanillin , which is used as a
flavouring additive in sweet foods such as ice cream.
O
CH3
H
OH
C
O
Vanillin
(a)
Identify two functional groups present in vanillin.
(b)
What is the strongest type of intermolecular force present between
molecules of vanillin?
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QUESTIONS
Question 5
The compounds shown below are active ingredients in over -the-counter
drugs. Aspirin is used as an analgesic (to relieve pain) and as an antipyretic
(to reduce elevated body temperatures). Ibuprofen is used as an anti inflammatory agent (to counteract swelling or inflammation of the joints, skin
and eyes).
OH
O
C
CH3
CH3
CH3
O
O
C
CH3
CH
CH
CH2
C
O
Aspirin
(acetylsalicylic acid)
OH
Ibuprofen
(a)
Which functional group is present in both drug molecules?
(b)
Which functional group is present in aspirin but not in ibuprofen?
CONSUMER CHEMISTRY (H, CHEMISTRY)
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9
QUESTIONS
Question 6
The two compounds shown below have similar molecular mass.
CH3
O
H
O
C
C
CH
CH2
CH2
CH
HO
N
C
C
CH3
Paracetamol
Molecular mass = 151 amu
(amu = atomic mass units)
CH2
CH3
Carvone
Molecular mass = 150 amu
(a)
Identify two different types of functional group present in paracetamol.
(b)
Identify two different types of functional group present in carvone.
(c)
In terms of intermolecular forces, explain why the melting point of
paracetamol (168°C) is significantly higher than that of carvo ne (25°C).
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QUESTIONS
Question 7
Capsaicin and zingerone are natural strong-smelling compounds found in
chilli pepper and ginger, respectively.
O
CH2 CH2 C
HO
CH3
CH3 O
Zingerone
H
CH2 N
HO
CH3
C
CH2 CH2 CH2 CH2 CH
CH
CH
CH3
O
CH3 O
Capsaicin
(a)
Identify the two circled functional groups in zingerone.
(b)
Identify the three circled functional groups in capsaicin.
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11
QUESTIONS
Question 8
Oil of wintergreen is an essential oil that is used in aromatherapy massage
blends for the joints and muscles. Methyl salicylate is the active ingredient of
oil of wintergreen.
O
CH3
C
O
OH
methyl salicylate
(a)
Identify the two circled functional groups present in methyl salicylate.
(b)
Explain whether the hydroxyl group contains a polar or a non -polar
bond.
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QUESTIONS
Question 9
Lycopene (C 40 H 56 ) is the red pigment found in tomatoes and other red fruits and vegetables.
CH3
H3C
CH3
C
CH
CH2 CH2 C
CH3
CH
CH
CH
C
CH3
CH
CH
CH
C
CH
CH
CH
CH
C
CH
CH
CH
CH3
Lycopene
C
CH
CH CH
CH3
C
CH2 CH2 CH
C
CH3
CH3
CH3
Astaxanthin (C 40 H 52 O 4 ) is a pink pigment found in salmon, trout, lobster and shrimp.
O
C
HO
CH3
CH3
CH3
C
CH
C
CH2 C
CH
CH
C
CH3
CH
CH
CH
C
CH3 C
CH
CH
CH
CH3
CH3
CH
C
CH
CH
CH3
Astaxanthin
(a)
Which functional group is found repeatedly throughout the structure of lycopene?
(b)
Name two additional functional groups that are found in the structure of astaxanthin.
(c)
Explain why astaxanthin (215°C) has a higher boiling point than lycopene (172°C).
CH
C
CH3
CH
CH
C
CH
C
CH3
CONSUMER CHEMISTRY (H, CHEMISTRY)
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CH2
C
O
13
OH
QUESTIONS
Question 10
Tetracycline is an antibiotic that is widely used as an alternative treatment for
patients who are allergic to penicillin. It prevents the growth of invading
bacteria, allowing the body’s own immune system to fight off infection.
CH3
N
CH3
HO
C
C
CH3
CH2
OH
CH
CH
CH
C
C
C
C
C
H
N
C
C
O
O
H
OH
OH
O
OH
Tetracycline
Identify four different types of functional group on the tetracycline structure.
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QUESTIONS
Question 11
L -tyrosine
is an important building block in the formation of almost all
proteins in the body.
NH2
HO
CH2 CH
O
C
OH
L-tyrosine
Identify three functional groups present in its structure.
CONSUMER CHEMISTRY (H, CHEMISTRY)
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15
QUESTIONS
Question 12
Alanine (2-aminopropanoic acid) is found in meat, fish, seafood and dairy
products.
CH3
H
N
CH
O
C
OH
H
alanine
Which functional groups are present in an alanine molecule?
A.
B.
C.
D.
Aldehyde, amine and hydroxyl
Ketone, amine and hydroxyl
Carboxyl and amine
Amino acid and hydroxyl
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QUESTIONS
Question 13
Aspirin and ibuprofen are common over -the-counter drugs.
OH
O
C
CH3
O
CH3
CH3
O
C
CH3
CH
CH
CH2
C
O
Aspirin
(acetylsalicylic acid)
OH
Ibuprofen
Identify the term that can be applied to aspirin but not to ibuprofen.
A.
B.
C.
D.
Aldehyde
Ketone
Carboxylic acid
Ester
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17
QUESTIONS
Question 14
Cyclohexyne is used in insect repellents.
H
H
H
C
H
C
C
H
C
C
C
H
H
H
cyclohexyne
Which of the following would be the best solvent for dissolving cycloh exyne?
A.
B.
C.
D.
Hexane
Hexanal
Hexanol
Hexanone
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ANSWERS
Answers
Question 1
Benzaldehyde is an aromatic compound with an almond -like smell, which is
used in flavourings and perfumes.
Circle and name the functional group on the benzaldehyde molecule below.
O
Carbonyl group
C
H
Benzaldehyde
CONSUMER CHEMISTRY (H, CHEMISTRY)
© Learning and Teaching Scotland 2010
19
ANSWERS
Question 2
Cholesterol is an important molecule present in the human body. However,
high levels of a certain type of cholesterol in the blood are linked with
illnesses such as heart disease and strokes.
CH2
HO
CH2
CH
C
CH2
Hydroxyl group
CH3
CH2
CH2
CH
C
CH3
C
CH
CH3
CH
CH
CH3
CH2
CH2
CH2
CH
CH2
CH
CH2
CH2
Carbon-to-carbon double bond Cholesterol
(a)
Identify the two circled functional groups on the cholesterol molecule
Hydroxyl group and carbon-to-carbon double bond.
(b)
Explain why this compound has a high boiling point.
Hydrogen bonding exists between the polar hydroxyl gro ups on
cholesterol molecules. Extra energy is required to overcome these
strong intermolecular forces of attraction, and therefore the boiling
point is high.
Additionally, cholesterol is a large molecule containing a large number
of electrons, which leads to relatively strong London forces existing
between cholesterol molecules. As more energy is therefore required to
separate the molecules, the boiling point is higher.
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CH2
CH3
ANSWERS
Question 3
β-carotene is a member of a family of chemicals called the carotenoids. It is
responsible for the orange colour in many fruits and vegetables, including
carrots.
CH3
CH3
CH3
CH2 C
CH2
C
CH2 C
CH
CH
C
CH3
CH
CH
CH
C
CH3 C
CH
CH
CH
CH3
CH3
CH
C
CH
CH
CH
CH3
CH3
(a)
Which functional group is present throughout the struc ture of βcarotene?
Carbon-to-carbon double bond.
(b)
Is the carbon-to-carbon double bond polar or non-polar?
Both atoms have the same electronegativity value (2.5) therefore the
bonds are non-polar covalent.
(c)
Which type of intermolecular forces will exis t between β-carotene
molecules?
London dispersion forces as the molecule does not contain polar bonds.
© Learning and Teaching Scotland 2010
CH
CH
C
C
CH3
-carotene
CONSUMER CHEMISTRY (H, CHEMISTRY)
C
21
C
C
ANSWERS
Question 4
The vanilla bean produces a compound called vanillin , which is used as a
flavouring additive in sweet foods such as ice cream.
O
CH3
H
OH
C
Hydroxyl group
O
Vanillin
Carbonyl group
(aldehyde)
(a)
Identify two functional groups present in vanillin.
Hydroxyl group and carbonyl group (aldehyde) .
(b)
What is the strongest type of intermolecular force present between
molecules of vanillin?
Hydrogen bonding due to the presence of hydroxyl groups.
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ANSWERS
Question 5
The compounds shown below are active ingredients in over -the-counter
drugs. Aspirin is used as an analgesic (to relieve pain) and as an antipyretic
(to reduce elevated body temperatures). Ibuprofen is used as an antiinflammatory agent (to counteract swelling or inflammation of the joints, skin
and eyes).
Carboxyl group
Carboxyl group
OH
O
C
CH3
O
CH3
CH3
O
C
CH3
CH
CH
CH2
O
OH
Ester link
Aspirin
(acetylsalicylic acid)
Ibuprofen
(a)
Which functional group is present in both drug molecules?
Carboxyl group.
(b)
Which functional group is present in aspirin but not in ibuprofen?
Ester link.
CONSUMER CHEMISTRY (H, CHEMISTRY)
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C
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ANSWERS
Question 6
The two compounds shown below have similar molecular mass.
Carbon-to-carbon
double bond
CH3
Amide link
H
O
O
C
C
CH
CH2
CH2
CH
Carbonyl group
HO
N
C
C
CH3
Hydroxyl group
Paracetamol
Molecular mass = 151 amu
(amu = atomic mass units)
CH2
CH3
Carvone
Molecular mass = 150 amu
(a)
Identify two different types of functional group present in paracetamol.
Hydroxyl group and amide link
(b)
Identify two different types of functional group present in carvone.
Carbonyl group and carbon-to-carbon double bond.
(c)
In terms of intermolecular forces, explain why the melting point of
paracetamol (168°C) is significantly higher than that of carvone (25°C).
Paracetamol contains the hydroxyl group, therefore hydrogen bonding
exists between its molecules. Permanent dipole–permanent dipole
interactions form between carvone molecules. Hydrogen bonds are an
unusually strong type of permanent dipole–permanent dipole
interactions, so more energy is required to overcome the intermolecular
forces of attraction between paracetamol molecules, and therefore
paracetemol has a higher boiling point than carvone.
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ANSWERS
Question 7
Capsaicin and zingerone are natural strong-smelling compounds found in
chilli pepper and ginger, respectively.
Carbonyl group
O
CH2 CH2 C
HO
CH3
CH3 O
Zingerone
Hydroxyl group
Carbon-to-carbon
double bond
H
CH2 N
HO
CH3
C
CH2 CH2 CH2 CH2 CH
CH
CH
CH3
O
CH3 O
Capsaicin
Amide link
(a)
Identify the two circled functional groups in zingerone.
Hydroxyl group and carbonyl group.
(b)
Identify the three circled functional groups in Capsaicin.
Hydroxyl group, amide link and carbon-to-carbon double bond.
CONSUMER CHEMISTRY (H, CHEMISTRY)
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25
ANSWERS
Question 8
Oil of wintergreen is an essential oil that is used in aromatherapy massage
blends for the joints and muscles. Methyl salicylate is the active ingredient of
oil of wintergreen.
O
CH3
C
O
OH
methyl salicylate
(a)
Identify the two circled functional groups present in methyl salicylate.
Ester link and hydroxyl group.
(b)
Explain whether the hydroxyl group contains a polar or a non -polar
bond.
The bond is polar because of the difference in electronegativity between
oxygen (3.5) and hydrogen (2.2).
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ANSWERS
Question 9
Lycopene (C 40 H 56 ) is the red pigment found in tomatoes and other red fruits and vegetables.
CH3
H3C
CH3
C
CH
CH2 CH2 C
CH3
CH
CH
CH
C
CH3
CH
CH
CH
C
CH
CH
CH
CH
C
CH
CH
CH
CH3
Lycopene
C
CH
CH CH
CH3
C
CH2 CH2 CH
CH3
C
CH3
CH3
Astaxanthin (C 40 H 52 O 4 ) is a pink pigment found in salmon, trout, lobs ter and shrimp.
O
C
HO
CH3
CH3
CH3
C
CH
C
CH2 C
CH
CH
C
CH3
CH
CH
CH
C
CH3 C
CH
CH
CH
CH3
CH3
CH
C
CH
CH
CH
CH3
Astaxanthin
C
CH
CH3
CH
CH2
C
CH
C
CH3
OH
C
O
(a)
Which functional group is found repeatedly througho ut the structure of lycopene?
Carbon-to-carbon double bond.
(b)
Name two additional functional groups that are found in the structure of astaxanthin.
Carbonyl group (ketone) and hydroxyl group.
(c)
Explain why astaxanthin (215°C) has a higher boiling point than lycopene (172°C).
Astaxanthin contains several polar groups and forms hydrogen bonding and other permanent dipole –permanent dipole
attractions between molecules. Lycopene contains no polar bonds, therefore only has London dispersion forces between
molecules. More energy is required to break the stronger attractive forces between astaxanthin molecules, so its boiling
point is higher.
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27
ANSWERS
Question 10
Tetracycline is an antibiotic that is widely used as an alternative treatment for
patients who are allergic to penicillin. It prevents the growth of invading
bacteria, allowing the body’s own immune system to fight off infection.
CH3
HO
C
CH2
CH
OH
CH
CH
C
C
CH3
N
CH3
C
C
C
H
C
N
C
C
O
O
H
OH
OH
O
OH
Tetracycline
Identify four different types of functional group on the tetracycline structure.
Amino group, carbonyl group, hydroxyl group and carbon-to-carbon double
bond.
28
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ANSWERS
Question 11
L -tyrosine
is an important building block in the formation of almost all
proteins in the body.
NH2
HO
CH2 CH
O
C
OH
L-tyrosine
Identify three functional groups present in its structure.
Amino group, hydroxyl group and carboxyl group.
CONSUMER CHEMISTRY (H, CHEMISTRY)
© Learning and Teaching Scotland 2010
29
ANSWERS
Question 12
Alanine (2-aminopropanoic acid) is found in meat, fish, seafood a nd dairy
products.
CH3
H
N
CH
O
C
OH
H
alanine
Which functional groups are present in an alanine molecule?
A.
Aldehyde, amine and hydroxyl
B.
Ketone, amine and hydroxyl
C.
Carboxyl and amine
D.
Amino acid and hydroxyl
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ANSWERS
Question 13
Aspirin and ibuprofen are common over-the-counter drugs.
OH
O
C
CH3
O
CH3
CH3
O
C
CH3
CH
C
CH
CH2
O
Aspirin
(acetylsalicylic acid)
OH
Ibuprofen
Identify the term that can be applied to aspirin but not to ibuprofen.
A.
Aldehyde
B.
Ketone
C.
Carboxylic acid
D.
Ester
CONSUMER CHEMISTRY (H, CHEMISTRY)
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31
ANSWERS
Question 14
Cyclohexyne is used in insect repellents.
H
H
H
C
H
C
C
H
C
C
C
H
H
H
cyclohexyne
Which of the following would be the best solvent for dissolving cyclohexyne?
A.
Hexane
B.
Hexanal
C.
Hexanol
D.
Hexanone
Cyclohexyne is a non-polar molecule, and therefore hexane (a non-polar
solvent) will dissolve it best.
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