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NATIONAL QUALIFICATIONS CURRICULUM SUPPORT

Chemistry

Consumer Chemistry

Predicting Physical Properties of Molecules from Functional Groups

[HIGHER]

The Scottish Qualifications Authority regularly reviews the arrangements for National Qualifications. Users of all NQ support materials, whether published by Learning and Teaching Scotland or others, are reminded that it is their responsibility to check that the support materials correspond to the requirements of the current arrangements.

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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© Learning and Teaching Scotland 2010

Contents

Introduction 4

Questions 5

Answers 19

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© Learning and Teaching Scotland 2010 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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© Learning and Teaching Scotland 2010 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) 5

© Learning and Teaching Scotland 2010 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 CH2 CH3 CH2 CH2 CH 3 CH3 CH3

HO CH C CH C CH CH CH2 CH2 CH2 CH2 CH3

CH2 C CH CH

CH2 CH CH CH2 2

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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© Learning and Teaching Scotland 2010 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.

CH CH3 3

CH3 CH3 CH2 C CH3 C CH2

CH2 C CH CH C CH CH CH C CH CH CH CH C CH CH CH C CH CH C CH2

CH2 C CH C CH 3 CH3 CH3 2

CH3 -carotene CH3

(a) Which functional group is present throughout the structure of β-carotene?

(b) Is the -to-carbon double bond polar or non-polar?

(c) Which type of intermolecular forces will exist between β-carotene molecules?

CONSUMER CHEMISTRY (H, CHEMISTRY) 7

© Learning and Teaching Scotland 2010 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

C OH

O

Vanillin

(a) Identify two functional groups present in vanillin.

(b) What is the strongest type of present between molecules of vanillin?

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© Learning and Teaching Scotland 2010 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).

O OH C

CH CH3 3 O CH3 O C CH C CH3 CH CH2

O OH

Aspirin (acetylsalicylic acid) Ibuprofen

(a) Which functional group is present in both drug molecules?

(b) Which functional group is present in aspirin but not in ibuprofen?

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© Learning and Teaching Scotland 2010 QUESTIONS

Question 6

The two compounds shown below have similar molecular mass.

CH3

O C C CH

H O CH2 CH2 CH HO N C C CH 3 CH2 CH3

Paracetamol Carvone

Molecular mass = 151 amu Molecular mass = 150 amu (amu = atomic mass units)

(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 carvone (25°C).

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© Learning and Teaching Scotland 2010 QUESTIONS

Question 7

Capsaicin and zingerone are natural strong-smelling compounds found in chilli pepper and ginger, respectively.

O

HO CH2 CH2 C

CH3

CH3 O Zingerone

H CH3

HO CH2 N 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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© Learning and Teaching Scotland 2010 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

C CH3 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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© Learning and Teaching Scotland 2010 QUESTIONS

Question 9

Lycopene (C40H56) is the red pigment found in tomatoes and other red fruits and vegetables.

CH3 CH3 CH3 CH3

H3C C CH CH2 CH2 C CH CH CH C CH CH CH C CH CH CH CH C CH CH CH C CH CH CH C CH2 CH2 CH C CH3

Lycopene CH3 CH3 CH3 CH3

Astaxanthin (C40H52O4) is a pink pigment found in salmon, trout, lobster and shrimp.

CH O CH3 3 CH CH C C 3 3 CH3 C CH2

HO CH C CH CH C CH CH CH C CH CH CH CH C CH CH CH C CH CH C CH OH

CH2 C CH C C 3 CH3 CH3

CH3 Astaxanthin CH3 O

(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).

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© Learning and Teaching Scotland 2010 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 CH3

HO CH3 N

C CH2 CH OH CH CH C H

C C C N C C C C H OH OH O OH O O

Tetracycline

Identify four different types of functional group on the tetracycline structure.

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© Learning and Teaching Scotland 2010 QUESTIONS

Question 11

L-tyrosine is an important building block in the formation of almost all in the body.

NH2 O

HO CH2 CH C OH

L-tyrosine

Identify three functional groups present in its structure.

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© Learning and Teaching Scotland 2010 QUESTIONS

Question 12

Alanine (2-aminopropanoic acid) is found in meat, fish, seafood and dairy products.

CH3 H O N CH C

H OH

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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© Learning and Teaching Scotland 2010 QUESTIONS

Question 13

Aspirin and ibuprofen are common over-the-counter drugs.

O OH C

CH O CH3 CH3 3 O C CH C CH3 CH CH2 O OH

Aspirin (acetylsalicylic acid) Ibuprofen

Identify the term that can be applied to aspirin but not to ibuprofen.

A. Aldehyde B. Ketone C. Carboxylic acid D. Ester

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© Learning and Teaching Scotland 2010 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. Hexane B. Hexanal C. Hexanol D. Hexanone

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© Learning and Teaching Scotland 2010 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 C H

Benzaldehyde

CONSUMER CHEMISTRY (H, CHEMISTRY) 19

© Learning and Teaching Scotland 2010 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 CH2 CH3 CH2 CH2 CH 3 CH3 CH3

HO CH C CH C CH CH CH2 CH2 CH2 CH2 CH3

CH2 C CH CH

CH2 Hydroxyl group CH CH CH2 2

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 groups 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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© Learning and Teaching Scotland 2010 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.

CH CH3 3

CH3 CH3 CH2 C CH3 C CH2

CH2 C CH CH C CH CH CH C CH CH CH CH C CH CH CH C CH CH C CH2

CH2 C CH C CH 3 CH3 CH3 2

CH3 -carotene CH3

(a) Which functional group is present throughout the structure of β- carotene? Carbon-to-carbon double bond.

(b) Is the carbon-to-carbon double bond polar or non-polar? Both have the same electronegativity value (2.5) therefore the bonds are non-polar covalent.

(c) Which type of intermolecular forces will exist between β-carotene molecules? London dispersion forces as the molecule does not contain polar bonds.

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© Learning and Teaching Scotland 2010 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

C OH

O Hydroxyl group

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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© Learning and Teaching Scotland 2010 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 anti- inflammatory agent (to counteract swelling or inflammation of the joints, skin and eyes).

Carboxyl group Carboxyl group O OH C

CH O CH3 CH3 3 O C CH C CH3 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.

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© Learning and Teaching Scotland 2010 ANSWERS

Question 6

The two compounds shown below have similar molecular mass.

Carbon-to-carbon CH3 double bond

Amide link O C C CH

CH CH H O 2 2 Carbonyl group CH HO N C C

CH3 CH2 CH3

Hydroxyl group Paracetamol Carvone

Molecular mass = 151 amu Molecular mass = 150 amu (amu = atomic mass units)

(a) Identify two different types of functional group present in paracetamol. Hydroxyl group and 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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© Learning and Teaching Scotland 2010 ANSWERS

Question 7

Capsaicin and zingerone are natural strong-smelling compounds found in chilli pepper and ginger, respectively.

Carbonyl group O

HO CH2 CH2 C

CH3

CH3 O Zingerone Hydroxyl group Carbon-to-carbon double bond

H CH3

HO CH2 N 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.

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© Learning and Teaching Scotland 2010 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

C CH3 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 (3.5) and hydrogen (2.2).

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© Learning and Teaching Scotland 2010 ANSWERS

Question 9

Lycopene (C40H56) is the red pigment found in tomatoes and other red fruits and vegetables.

CH3 CH3 CH3 CH3

H3C C CH CH2 CH2 C CH CH CH C CH CH CH C CH CH CH CH C CH CH CH C CH CH CH C CH2 CH2 CH C CH3

Lycopene CH3 CH3 CH3 CH3

Astaxanthin (C40H52O4) is a pink pigment found in salmon, trout, lobster and shrimp.

CH O CH3 3 CH CH C C 3 3 CH3 C CH2

HO CH C CH CH C CH CH CH C CH CH CH CH C CH CH CH C CH CH C CH OH

CH2 C CH C C 3 CH3 CH3 CH CH 3 Astaxanthin 3 O

(a) Which functional group is found repeatedly throughout 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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© Learning and Teaching Scotland 2010 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 CH3

HO CH3 N

C CH2 CH OH CH CH C H

C C C N C C C C H OH OH O OH O O

Tetracycline

Identify four different types of functional group on the tetracycline structure. Amino group, carbonyl group, hydroxyl group and carbon-to-carbon double bond.

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© Learning and Teaching Scotland 2010 ANSWERS

Question 11

L-tyrosine is an important building block in the formation of almost all proteins in the body.

NH2 O

HO CH2 CH C OH

L-tyrosine

Identify three functional groups present in its structure. Amino group, hydroxyl group and carboxyl group.

CONSUMER CHEMISTRY (H, CHEMISTRY) 29

© Learning and Teaching Scotland 2010 ANSWERS

Question 12

Alanine (2-aminopropanoic acid) is found in meat, fish, seafood and dairy products.

CH3 H O N CH C

H OH

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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© Learning and Teaching Scotland 2010 ANSWERS

Question 13

Aspirin and ibuprofen are common over-the-counter drugs.

O OH C

O CH3 CH CH3 3 C O

CH C CH3 CH CH2 O OH

Aspirin (acetylsalicylic acid) 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) 31

© Learning and Teaching Scotland 2010 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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© Learning and Teaching Scotland 2010