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. 2 CONSUMER CHEMISTRY (H, CHEMISTRY) © Learning and Teaching Scotland 2010 Contents Introduction 4 Questions 5 Answers 19 CONSUMER CHEMISTRY (H, CHEMISTRY) 3 © 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. 4 CONSUMER CHEMISTRY (H, CHEMISTRY) © 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. 6 CONSUMER CHEMISTRY (H, CHEMISTRY) © 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 carbon-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 intermolecular force present between molecules of vanillin? 8 CONSUMER CHEMISTRY (H, CHEMISTRY) © 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? CONSUMER CHEMISTRY (H, CHEMISTRY) 9 © 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). 10 CONSUMER CHEMISTRY (H, CHEMISTRY) © 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. CONSUMER CHEMISTRY (H, CHEMISTRY) 11 © 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. 12 CONSUMER CHEMISTRY (H, CHEMISTRY) © 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). CONSUMER CHEMISTRY (H, CHEMISTRY) 13 © 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. 14 CONSUMER CHEMISTRY (H, CHEMISTRY) © Learning and Teaching Scotland 2010 QUESTIONS 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. CONSUMER CHEMISTRY (H, CHEMISTRY) 15 © 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 16 CONSUMER CHEMISTRY (H, CHEMISTRY) © Learning and Teaching Scotland 2010 QUESTIONS Question 13 Aspirin and ibuprofen are common over-the-counter drugs. O OH C CH CH3 3 O CH3 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 CONSUMER CHEMISTRY (H, CHEMISTRY) 17 © 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 18 CONSUMER CHEMISTRY (H, CHEMISTRY) © 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 Carbonyl group 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.