november 2015 chemistry standard level paper 1
TRANSCRIPT
N15/4/CHEMI/SPM/ENG/TZ0/XX/M
2 pages
Markscheme
November 2015
Chemistry
Standard level
Paper 1
– 2 – N15/4/CHEMI/SPM/ENG/TZ0/XX/M
1. C 16. A 31. – 46. – 2. C 17. B 32. – 47. – 3. C 18. D 33. – 48. – 4. A 19. C 34. – 49. – 5. A 20. D 35. – 50. – 6. B 21. A 36. – 51. – 7. B 22. A 37. – 52. – 8. B 23. A 38. – 53. – 9. B 24. C 39. – 54. – 10. D 25. D 40. – 55. – 11. A 26. B 41. – 56. – 12. B 27. A 42. – 57. – 13. D 28. C 43. – 58. – 14. D 29. D 44. – 59. – 15. B 30. C 45. – 60. –
N16/4/CHEMI/SPM/ENG/TZ0/XX/M
2 pages
Markscheme
November 2016
Chemistry
Standard level
Paper 1
– 2 – N16/4/CHEMI/SPM/ENG/TZ0/XX/M
1. C 16. C 31. – 46. – 2. D 17. B 32. – 47. – 3. C 18. A 33. – 48. – 4. B 19. A 34. – 49. – 5. C 20. D 35. – 50. – 6. A 21. B 36. – 51. – 7. A 22. D 37. – 52. – 8. C 23. C 38. – 53. – 9. D 24. A 39. – 54. – 10. A 25. A 40. – 55. – 11. D 26. B 41. – 56. – 12. D 27. A 42. – 57. – 13. C 28. D 43. – 58. – 14. B 29. B 44. – 59. – 15. C 30. B 45. – 60. –
N16/4/CHEMI/SP2/ENG/TZ0/XX
© International Baccalaureate Organization 201614 pages8816 – 6105
ChemistryStandard levelPaper 2
Candidate session number
1 hour 15 minutes
Instructions to candidates
Write your session number in the boxes above. Do not open this examination paper until instructed to do so. Answer all questions. Write your answers in the boxes provided. A calculator is required for this paper. A clean copy of the chemistry data booklet is required for this paper. The maximum mark for this examination paper is [50 marks].
Monday 14 November 2016 (morning)
16EP01
– 2 –
Answer all questions. Write your answers in the boxes provided.
1. Ethane-1,2-diol, HOCH2CH2OH, has a wide variety of uses including the removal of ice from aircraft and heat transfer in a solar cell.
(a) Ethane-1,2-diol can be formed according to the following reaction.
2CO (g) + 3H2 (g) HOCH2CH2OH (g)
(i) Deduce the equilibrium constant expression, Kc , for this reaction. [1]
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(ii) State how increasing the pressure of the reaction mixture at constant temperature will affect the position of equilibrium and the value of Kc . [2]
Position of equilibrium:
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Kc:
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(iii) Calculatetheenthalpychange,∆H Ö, in kJ, for this reaction using section 11 of the data booklet. The bond enthalpy of the carbon–oxygen bond in CO (g) is 1077 kJ mol-1. [3]
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(This question continues on the following page)
16EP02
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– 3 –
Turn over
(Question 1 continued)
(iv) Theenthalpychange,∆H Ö, for the following similar reaction is –233.8 kJ.
2CO (g) + 3H2 (g) HOCH2CH2OH (l)
Deduce why this value differs from your answer to (a)(iii). [1]
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(b) Determine the average oxidation state of carbon in ethene and in ethane-1,2-diol. [2]
Ethene:
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Ethane-1,2-diol:
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(c) Explainwhytheboilingpointofethane-1,2-diolissignificantlygreaterthanthatofethene. [2]
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(d) Ethane-1,2-diolcanbeoxidizedfirsttoethanedioicacid,(COOH)2, and then to carbon dioxide and water. Suggest the reagents to oxidize ethane-1,2-diol. [1]
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16EP03
N16/4/CHEMI/SP2/ENG/TZ0/XX
– 4 –
2. The concentration of a solution of a weak acid, such as ethanedioic acid, can be determined by titration with a standard solution of sodium hydroxide, NaOH (aq).
(a) Distinguish between a weak acid and a strong acid. [1]
Weak acid:
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Strong acid:
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(b) Suggest why it is more convenient to express acidity using the pH scale instead of using the concentration of hydrogen ions. [1]
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(c) 5.00 g of an impure sample of hydrated ethanedioic acid, (COOH)2•2H2O, was dissolved in water to make 1.00 dm3 of solution. 25.0 cm3 samples of this solution were titrated against a 0.100 mol dm-3 solution of sodium hydroxide using a suitable indicator.
(COOH)2 (aq) + 2NaOH (aq) → (COONa)2 (aq) + 2H2O (l)
The mean value of the titre was 14.0 cm3.
(i) Calculate the amount, in mol, of NaOH in 14.0 cm3 of 0.100 mol dm-3 solution. [1]
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(This question continues on the following page)
16EP04
N16/4/CHEMI/SP2/ENG/TZ0/XX
– 5 –
Turn over
(Question 2 continued)
(ii) Calculate the amount, in mol, of ethanedioic acid in each 25.0 cm3 sample. [1]
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(iii) Determine the percentage purity of the hydrated ethanedioic acid sample. [3]
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(d) The Lewis (electron dot) structure of the ethanedioate ion is shown below.
C C
O
O O
O2–
Outline why all the C–O bond lengths in the ethanedioate ion are the same length and suggest a value for them. Use section 10 of the data booklet. [2]
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16EP05
N16/4/CHEMI/SP2/ENG/TZ0/XX
– 6 –
Please do not write on this page.
Answers written on this page will not be marked.
16EP06
N16/4/CHEMI/SP2/ENG/TZ0/XX
– 7 –
Turn over
3. Sodium thiosulfate solution reacts with dilute hydrochloric acid to form a precipitate of sulfur at room temperature.
Na2S2O3 (aq) + 2HCl (aq) → S (s) + SO2 (g) + 2NaCl (aq) + X
(a) Identify the formula and state symbol of X. [1]
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(b) Suggest why the experiment should be carried out in a fume hood or in a well-ventilated laboratory. [1]
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(This question continues on the following page)
16EP07
N16/4/CHEMI/SP2/ENG/TZ0/XX
– 8 –
(Question 3 continued)
(c) The precipitate of sulfur makes the mixture cloudy, so a mark underneath the reaction mixture becomes invisible with time.
mark mark mark
Glass
mark
10.0 cm3 of 2.00 mol dm-3 hydrochloric acid was added to a 50.0 cm3 solution of sodium thiosulfate at temperature, T1. Students measured the time taken for the mark to be no longer visible to the naked eye. The experiment was repeated at different concentrations of sodium thiosulfate.
Experiment [Na2S2O3 (aq)]/ mol dm-3
Time, t, for mark to disappear / s ± 1 s
1t
* / 10-3 s-1
1 0.150 23 43.52 0.120 27 37.03 0.090 36 27.84 0.060 60 16.75 0.030 111 9.0
* The reciprocal of the time in seconds can be used as a measure of the rate of reaction.
[Source:Adaptedfromhttp://www.flinnsci.com/]
Showthatthehydrochloricacidaddedtotheflaskinexperiment1isinexcess. [2]
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(This question continues on the following page)
16EP08
N16/4/CHEMI/SP2/ENG/TZ0/XX
– 9 –
Turn over
(Question 3 continued)
(d) Drawthebestfitlineof1t
against concentration of sodium thiosulfate on the axes provided. [2]
Rat
e of
reac
tion 1 t
/ 10-
3 s-1
0.03 0.06 0.09 0.12 0.150
5
10
15
20
25
30
35
40
45
[Na2S2O3] / mol dm-3
(e) A student decided to carry out another experiment using 0.075 mol dm-3 solution of sodium thiosulfate under the same conditions. Determine the time taken for the mark to be no longer visible. [2]
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(This question continues on the following page)
16EP09
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(Question 3 continued)
(f) An additional experiment was carried out at a higher temperature, T2.
(i) On the same axes, sketch Maxwell–Boltzmann energy distribution curves at the two temperatures T1 and T2, where T2 > T1. [2]
(ii) Explain why a higher temperature causes the rate of reaction to increase. [2]
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(g) Suggest one reason why the values of rates of reactions obtained at higher temperatures may be less accurate. [1]
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(This question continues on the following page)
16EP10
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Turn over
4. Magnesium is a group 2 metal which exists as a number of isotopes and forms many compounds.
(a) State the nuclear symbol notation, AZ X, for magnesium-26. [1]
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(b) Mass spectroscopic analysis of a sample of magnesium gave the following results:
% abundanceMg-24 78.60Mg-25 10.11Mg-26 11.29
Calculate the relative atomic mass, Ar , of this sample of magnesium to two decimal places. [2]
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(c) Magnesium burns in air to form a white compound, magnesium oxide. Formulate an equation for the reaction of magnesium oxide with water. [1]
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(This question continues on the following page)
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(Question 4 continued)
(d) Describe the trend in acid-base properties of the oxides of period 3, sodium to chlorine. [2]
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(e) In addition to magnesium oxide, magnesium forms another compound when burned in air. Suggest the formula of this compound. [1]
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(f) Describe the structure and bonding in solid magnesium oxide. [2]
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(g) Magnesium chloride can be electrolysed.
Deduce the half-equations for the reactions at each electrode when molten magnesium chloride is electrolysed, showing the state symbols of the products. The melting points of magnesium and magnesium chloride are 922 K and 987 K respectively. [2]
Anode (positive electrode):
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Cathode (negative electrode):
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16EP12
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5. Propane and propene are members of different homologous series.
(a) Draw the full structural formulas of propane and propene. [1]
Propane:
Propene:
(b) Both propane and propene react with bromine.
(i) State an equation and the condition required for the reaction of 1 mol of propane with 1 mol of bromine. [2]
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(ii) State an equation for the reaction of 1 mol of propene with 1 mol of bromine. [1]
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(Question 5 continued)
(iii) State the type of each reaction with bromine. [1]
Propane:
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Propene:
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16EP14
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Please do not write on this page.
Answers written on this page will not be marked.
16EP15
Please do not write on this page.
Answers written on this page will not be marked.
16EP16
N16/4/CHEMI/SP3/ENG/TZ0/XX
Candidate session number
ChemistryStandard levelPaper 3
© International Baccalaureate Organization 201630 pages
1 hour
Tuesday 15 November 2016 (morning)
8816 – 6106
Instructions to candidates
• Write your session number in the boxes above.• Do not open this examination paper until instructed to do so.• Answers must be written within the answer boxes provided.• A calculator is required for this paper.• A clean copy of the chemistry data booklet is required for this paper.• The maximum mark for this examination paper is [35 marks].
Section A Questions
Answer all questions. 1 – 2
Section B Questions
Answer all of the questions from one of the options.
Option A — Materials 3 – 7
Option B — Biochemistry 8 – 10
Option C — Energy 11 – 15
Option D — Medicinal chemistry 16 – 20
32EP01
– 2 –
Section A
Answer all questions. Write your answers in the boxes provided.
1. In order to provide safe drinking water, a water supply is often treated with disinfectants, which aim to inactivate disease-causing bacteria in the water.
To compare the effectiveness of different disinfectants, a CT value is used as a measure of the dosage of disinfectant needed to achieve a certain level of inactivation of specific bacteria.
CT value (mg min dm−3) = C (mg dm−3) × T (min) concentration contact time of disinfectant with water
(a) The table below compares the CT values of different disinfectants necessary to achieve 99 % inactivation of two types of bacteria, listed as A and B.
DisinfectantCT value / mg min dm−3 for 99 % inactivation of bacteria
Bacterium A Bacterium BHypochlorous acid, HOCl 4 × 10−2 8 × 10−2
Hypochlorite ion, OCl− 9.2 × 10−1 3.3Chlorine dioxide, ClO2 1.8 × 10−1 1.3 × 10−1
Monochloramine, NH2Cl 64 94
(i) Deduce the oxidation state of chlorine in the following disinfectants. [1]
HOCl:
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ClO2:
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(This question continues on the following page)
32EP02
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Turn over
(Question 1 continued)
(ii) From the data on CT values, justify the statement that bacterium B is generally more resistant to disinfection than bacterium A. [1]
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(iii) CT values can be used to determine whether a particular treatment process is adequate. Calculate the CT value, in mg min dm−3, when 1.50 × 10−5 g dm−3 of chlorine dioxide is added to a water supply with a contact time of 9.82 minutes. [1]
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(iv) From your answer to (a) (iii) and the data in the table, comment on whether this treatment will be sufficient to inactivate 99 % of bacterium A. [1]
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(This question continues on the following page)
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(Question 1 continued)
(b) CT values are influenced by temperature and by pH. The table below shows the CT values for chlorine needed to achieve 99 % inactivation of a specific bacterium at stated values of pH and temperature.
pHTemperature / °C
0.5 5.0 10.0 15.0 20.06.0 97 69 52 35 267.0 137 97 73 49 378.0 197 140 105 70 539.0 281 201 151 101 75
(i) With reference to the temperature data in the table, suggest why it may be more difficult to treat water effectively with chlorine in cold climates. [1]
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(ii) Sketch a graph on the axes below to show how the CT value (at any temperature) varies with pH. [1]
(This question continues on the following page)
32EP04
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Turn over
(Question 1 continued)
(iii) Comment on the relative CT values at pH 6.0 and pH 9.0 at each temperature. [1]
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(iv) Chlorine reacts with water as follows:
Cl2 (g) + H2O (l) HOCl (aq) + HCl (aq)
HOCl (aq) OCl− (aq) + H+ (aq)
Predict how the concentrations of each of the species HOCl (aq) and OCl− (aq) will change if the pH of the disinfected water increases. [1]
HOCl (aq):
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OCl− (aq):
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(c) Despite widespread improvements in the provision of safe drinking water, the sale of bottled water has increased dramatically in recent years. State one problem caused by this trend. [1]
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32EP05
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2. In a class experiment, students were asked to determine the value of x in the formula of a hydrated salt, BaCl2・ xH2O. They followed these instructions:
1. Measure the mass of an empty crucible and lid.2. Add approximately 2 g sample of hydrated barium chloride to the crucible and record
the mass.3. Heat the crucible using a Bunsen burner for five minutes, holding the lid at an angle
so gas can escape.4. After cooling, reweigh the crucible, lid and contents.5. Repeat steps 3 and 4.
Their results in three trials were as follows:
Trial 1 Trial 2 Trial 3Mass of crucible + lid / g ±0.001 20.088 20.122 20.105Mass of crucible + lid + BaCl2・ xH2O before heating / g ±0.001 22.166 22.184 22.186Mass of crucible + lid + BaCl2 after 1st heating / g ±0.001 21.859 22.080 21.926Mass of crucible + lid + BaCl2 after 2nd heating / g ±0.001 21.859 21.865 21.927
(a) State and explain the further work students need to carry out in trial 2 before they can process the results alongside trial 1. [2]
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(b) In trial 3, the students noticed that after heating, the crucible had turned black on the outside. Suggest what may have caused this, and how this might affect the calculated value for x in the hydrated salt. [2]
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(This question continues on the following page)
32EP06
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Turn over
(Question 2 continued)
(c) List two assumptions made in this experiment. [2]
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32EP07
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Section B
Answer all of the questions from one of the options.
Option A — Materials
3. Materials science involves understanding the properties of materials and applying those properties to desired structures.
(a) Magnesium oxide, MgO, and silicon carbide, SiC, are examples of ceramic materials. State the name of the predominant type of bonding in each material. [1]
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(b) Predict the predominant type of bonding for a binary compound AB in which the electronegativity of both atoms is low. Use section 29 of the data booklet. [1]
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4. A student wanted to determine the formula of indium sulfate. She applied an electrical current of 0.300 A to an aqueous solution of indium sulfate for 9.00 × 103 s and found that 1.07 g of indium metal deposited on the cathode.
(a) Calculate the charge, in coulombs, passed during the electrolysis.
currentchargetime
IQt
=
[1]
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(Option A continues on the following page)
32EP08
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Turn over
(Option A, question 4 continued)
(b) Calculate the amount, in mol, of electrons passed using section 2 of the data booklet. [1]
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(c) Calculate the mass of indium deposited by one mole of electrons. [1]
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(d) Calculate the number of moles of electrons required to deposit one mole of indium. Relative atomic mass of indium, Ar = 114.82. [1]
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(e) Deduce the charge on the indium ion and the formula of indium sulfate. [1]
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(Option A continues on the following page)
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(Option A continued)
5. Research has led to the discovery of new catalysts that are in high demand and used in many chemical industries.
(a) Explain, with reference to their structure, the great selectivity of zeolites as catalysts. [2]
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(b) Nanocatalysts play an essential role in the manufacture of industrial chemicals.
(i) Describe the high pressure carbon monoxide (HIPCO) method for the production of carbon nanotubes. [2]
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(ii) Outline one benefit of using nanocatalysts compared to traditional catalysts in industry. [1]
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(Option A continues on the following page)
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(Option A continued)
6. Polymers are made up of repeating monomer units which can be manipulated in various ways to give structures with desired properties.
(a) (i) Draw the structure of 2-methylpropene. [1]
(ii) Deduce the repeating unit of poly(2-methylpropene). [1]
(b) Deduce the percentage atom economy for polymerization of 2-methylpropene. [1]
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(c) (i) Suggest why incomplete combustion of plastic, such as polyvinyl chloride, is common in industrial and house fires. [1]
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(Option A continues on the following page)
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(Option A, question 6 continued)
(ii) Phthalate plasticizers such as DEHP, shown below, are frequently used in polyvinyl chloride.
C
C
O
O
O
O
CH2
CH2
CH
CH CH2
CH2
CH2
CH2
CH3
CH3
CH2
CH2
CH2
CH2
CH3
CH3
With reference to bonding, suggest a reason why many adults have measurable levels of phthalates in their bodies. [1]
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7. Liquid crystals have many applications.
(a) Outline how a lyotropic liquid crystal differs from a thermotropic liquid crystal. [2]
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(Option A continues on the following page)
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(Option A, question 7 continued)
(b) Explain the effect of increasing the temperature of a nematic liquid crystal on its directional order. [1]
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End of Option A
32EP13
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Option B — Biochemistry
8. Lipids are an important part of the human diet.
(a) Fatty acids react with glycerol to form fats and oils. State the name of the chemical link formed in this reaction and the name of the other product. [1]
Name of the chemical link:
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Name of the other product:
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(b) The table below shows average figures for the percentage fatty acid composition of some common fats and oils.
Source of fat or oil
% saturated fatty acids
(total)
% monounsaturated fatty acid oleic
% polyunsaturated fatty acids
linoleic linolenic
Beef fat 59 38 3 -Coconut oil 90 8 2 -Corn oil 25 26 47 2Cotton seed oil 22 35 43 -Olive oil 15 78 7 -Soybean oil 14 28 50 8
(i) Deduce, with a reason, which fat or oil from the table above has the lowest iodine number. [1]
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(ii) Deduce, with a reason, which fat or oil from the table above is most likely to become rancid when exposed to the air. [1]
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(Option B continues on the following page)
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(Option B, question 8 continued)
(iii) The P/S index of a fat or oil is the ratio of polyunsaturated fat to saturated fat present. It is sometimes used to compare the relative health benefits of different lipids in the diet. Calculate the P/S index of beef fat and soybean oil. [1]
Beef fat:
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Soybean oil:
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(iv) Suggest why a P/S index of greater than 1 is considered beneficial to health. [1]
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(v) Cotton seed oil and corn oil have similar iodine numbers but the melting point of cotton seed oil is higher than that of corn oil. Suggest an explanation in terms of the structure and bonding in these two oils. [2]
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(Option B continues on the following page)
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(Option B continued)
9. Carbohydrates are energy-rich molecules which can be synthesized in some plant cells from inorganic compounds.
(a) State the raw materials and source of energy used in the process described above. [1]
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(b) The structures of two molecules, X and Y, are shown below.
X: Y:H
C
O
CH OH
CH OH
H
C
C O
CH OH
H
H
OHH
H
C
O
CH OH
CH OH
H
C
C O
CH OH
H
H
OHH
(i) Justify why both these molecules are carbohydrates. [1]
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(ii) Distinguish between these molecules in terms of their functional groups. [1]
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(Option B continues on the following page)
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(Option B, question 9 continued)
(c) Amylose is an unbranched polysaccharide composed of repeating units of glucose.
(i) Draw the structure of the repeating unit of amylose. Use section 34 of the data booklet. [1]
(ii) Amylose is a major component of starch. Corn starch can be used to make replacements for plastics derived from oil, especially for packaging. Discuss one potential advantage and one disadvantage of this use of starch. [2]
Advantage:
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Disadvantage:
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(Option B continues on the following page)
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(Option B continued)
10. Amino acids are usually identified by their common names. Use section 33 of the data booklet.
(a) State the IUPAC name for leucine. [1]
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(b) A mixture of amino acids is separated by gel electrophoresis at pH 6.0. The amino acids are then stained with ninhydrin.
(i) On the diagram below draw the relative positions of the following amino acids at the end of the process: Val, Asp, Lys and Thr. [2]
Origin
(+)Anode
(−)Cathode
(ii) Suggest why glycine and isoleucine separate slightly at pH 6.5. [1]
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(c) Determine the number of different tripeptides that can be made from twenty different amino acids. [1]
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(Option B continues on the following page)
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(Option B, question 10 continued)
(d) The fibrous protein keratin has a secondary structure with a helical arrangement.
(i) State the type of interaction responsible for holding the protein in this arrangement. [1]
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(ii) Identify the functional groups responsible for these interactions. [1]
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End of Option B
32EP19
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Option C — Energy
11. Chemical energy from redox reactions can be used as a portable source of electrical energy. A hybrid car uses a lithium ion battery in addition to gasoline as fuel.
(a) (i) Calculate the specific energy of the lithium ion battery, in MJ kg−1, when 80.0 kg of fuel in the battery releases 1.58 × 107 J. Use section 1 of the data booklet. [1]
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(ii) The specific energy of gasoline is 46.0 MJ kg−1. Suggest why gasoline may be considered a better energy source than the lithium ion battery based on your answer to part (a) (i). [1]
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(b) (i) The energy density of gasoline is 34.3 MJ dm−3. Calculate the volume of gasoline, in dm3, that is equivalent to the energy in 80.0 kg of fuel in the lithium ion battery. Use section 1 of the data booklet. [1]
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(ii) The efficiency of energy transfer by this lithium ion battery is four times greater than that of gasoline. Determine the distance, in km, the car can travel on the lithium ion battery power alone if the gasoline-powered car uses 1.00 dm3 gasoline to travel 32.0 km. [1]
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(Option C continues on the following page)
32EP20
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Turn over
(Option C continued)
12. Auto-ignition of hydrocarbon fuel in a car engine causes “knocking”. The tendency of a fuel to knock depends on its molecular structure.
(a) Discuss how the octane number changes with the molecular structure of the alkanes. [2]
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(b) Catalytic reforming and cracking reactions are used to produce more efficient fuels. Deduce the equation for the conversion of heptane to methylbenzene. [1]
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13. Carbon dioxide and water vapour are greenhouse gases produced by the combustion of fossil fuels.
(a) Explain the effect of the increasing concentration of atmospheric carbon dioxide on the acidity of oceans. [2]
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(Option C continues on the following page)
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(Option C, question 13 continued)
(b) (i) Describe the changes that occur at the molecular level when atmospheric carbon dioxide gas absorbs infrared radiation emitted from the Earth’s surface. [2]
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(ii) Other than changes to the acidity of oceans, suggest why the production of carbon dioxide is of greater concern than the production of water vapour. [1]
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14. Biofuels are renewable energy sources derived mainly from plants.
(a) State the equation for the complete transesterification of the triglyceride given below with methanol. [2]
H2 CO C17H33
HC
H2C
O CO C17H33
O CO C17H33
(Option C continues on the following page)
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Turn over
(Option C, question 14 continued)
(b) Outline why the fuel produced by the reaction in (a) is more suitable for use in diesel engines than vegetable oils. [1]
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15. Nuclear reactions transform one nuclide into another. Fission, splitting a large nucleus into two smaller nuclei, releases vast amounts of energy.
(a) (i) Explain why fusion, combining two smaller nuclei into a larger nucleus, releases vast amounts of energy. Use section 36 of the data booklet. [2]
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(ii) Outline one advantage of fusion as a source of energy. [1]
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(Option C continues on the following page)
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(Option C, question 15 continued)
(b) Radioactive phosphorus, 33P, has a half-life of 25.3 days.
(i) Calculate 33P decay constant λ and state its unit. Use section 1 of the data booklet. [1]
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(ii) Determine the fraction of the 33P sample remaining after 101.2 days. [1]
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End of Option C
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Turn over
Option D — Medicinal chemistry
16. Penicillin is an antibiotic which contains a beta-lactam ring. Its general structure is shown below.
R
C
HN
O
N
O
SCH3
CH3
CO
HO
(a) (i) Outline what is meant by the term “ring strain”. [1]
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(ii) On the diagram above, label with asterisk/s (*) the carbon atom/s that experience ring strain. [1]
(b) (i) Some antibiotic-resistant bacteria produce a beta-lactamase enzyme which destroys penicillin activity. Suggest how adding clavulanic acid to penicillin enables the antibiotic to retain its activity.
O
N
O
COOH
H
CH2OH
Clavulanic acid
[1]
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(Option D continues on the following page)
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(Option D, question 16 continued)
(ii) Populations of antibiotic-resistant bacteria have increased significantly over the last 60 years. Outline why antibiotics such as penicillin should not be prescribed to people suffering from a viral infection. [2]
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17. Oseltamivir (Tamiflu) and zanamivir (Relenza) are both used as antivirals to help prevent the spread of the flu virus, but are administered by different methods.
(a) Zanamivir must be taken by inhalation, not orally. Deduce what this suggests about the bioavailability of zanamivir if taken orally. [1]
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(b) Oseltamivir does not possess the carboxyl group needed for activity until it is chemically changed in the body. Deduce the name of the functional group in oseltamivir which changes into a carboxyl group in the body. Use section 37 of the data booklet. [1]
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(c) The synthesis of oseltamivir is dependent on a supply of the precursor shikimic acid, which is available only in low yield from certain plants, notably Chinese star anise. State one alternative green chemistry source of shikimic acid. [1]
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(Option D continues on the following page)
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(Option D continued)
18. The mild analgesic aspirin can be prepared in the laboratory from salicylic acid.
(CH3CO)2O + HOC6H4COOH → CH3CO2C6H4COOH + CH3COOH
Salicylic acid Aspirin
After the reaction is complete, the product is isolated, recrystallized, tested for purity and the experimental yield is measured. A student’s results in a single trial are as follows.
Mass / g ±0.001 Melting point / °C ±1Initial salicylic acid 1.552Crude product 1.398 106–114Product after recrystallization 1.124 122–125
Literature melting point data: aspirin = 138–140 °C
(a) Determine the percentage experimental yield of the product after recrystallization. The molar masses are as follows: M (salicylic acid) = 138.13 g mol−1, M (aspirin) = 180.17 g mol−1. (You do not need to process the uncertainties in the calculation.) [2]
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(b) Suggest why isolation of the crude product involved the addition of ice-cold water. [1]
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(Option D continues on the following page)
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(Option D, question 18 continued)
(c) Justify the conclusion that recrystallization increased the purity of the product, by reference to two differences between the melting point data of the crude and recrystallized products. [2]
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(d) State why aspirin is described as a mild analgesic with reference to its site of action. [1]
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19. Excess stomach acid leads to medical conditions that affect many people worldwide. These conditions can be treated with several types of medical drugs.
(a) Ranitidine (Zantac) is a drug that inhibits stomach acid production. Outline why the development of this drug was based on a detailed knowledge of the structure of histamine, shown below. [1]
HN
N
NH2
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(Option D continues on the following page)
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(Option D, question 19 continued)
(b) Two other drugs, omeprazole (Prilosec) and esomeprazole (Nexium), directly prevent the release of acid into the stomach. Identify the site of action in the body. [1]
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(c) A different approach to treating excess stomach acid is to neutralize it with antacids. Formulate an equation that shows the action of an antacid that can neutralize three moles of hydrogen ions, H+, per mole of antacid. [1]
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(Option D continues on the following page)
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(Option D continued)
20. Methadone, a synthetic opioid, binds to opioid receptors in the brain.
CH2
O
CH2
H3C CH
H3C N
H3C
CH3
Methadone
(a) Compare and contrast the functional groups present in methadone and diamorphine (heroin), giving their names. Use section 37 of the data booklet. [2]
One similarity:
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One difference:
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(b) Methadone is sometimes used to help reduce withdrawal symptoms in the treatment of heroin addiction. Outline one withdrawal symptom that an addict may experience. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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End of Option D
32EP30
N16/4/CHEMI/SP3/ENG/TZ0/XX
Please do not write on this page.
Answers written on this page will not be marked.
32EP31
Please do not write on this page.
Answers written on this page will not be marked.
32EP32
ChemistryStandard levelPaper 1
13 pages
Wednesday 8 November 2017 (afternoon)
45 minutes
N17/4/CHEMI/SPM/ENG/TZ0/XX
© International Baccalaureate Organization 20178817 – 6104
Instructions to candidates
• Do not open this examination paper until instructed to do so.• Answer all the questions.• For each question, choose the answer you consider to be the best and indicate your choice on
the answer sheet provided.• The periodic table is provided for reference on page 2 of this examination paper.• The maximum mark for this examination paper is [30 marks].
88 Ra
(226
)
56 Ba
137.
33
38 Sr87
.62
20 Ca
40.0
8
12 Mg
24.3
1
4 Be
9.012
‡†
89 ‡
Ac
(227
)
57 †
La13
8.91
39 Y88
.91
21 Sc 44.9
6
90 Th23
2.04
58 Ce
140.
12
72 Hf
178.
49
40 Zr 91.2
2
22 Ti47
.87
91 Pa23
1.04
59 Pr14
0.91
73 Ta18
0.95
41 Nb
92.9
1
23 V50
.94
92 U23
8.03
60 Nd
144.
24
74 W18
3.84
42 Mo
95.9
6
24 Cr
52.0
0
55 Cs
132.
91
37 Rb
85.4
7
19 K39
.10
11 Na
22.9
9
3 Li 6.941 H 1.011 Fr87 (223
)
93 Np
(237
)
61 Pm (145
)
75 Re
186.
21
43 Tc (98)25 Mn
54.9
4
94 Pu (244
)
62 Sm15
0.36
76 Os
190.
23
44 Ru
101.
07
26 Fe 55.8
5
95 Am
(243
)
63 Eu15
1.96
77 Ir19
2.22
45 Rh
102.
91
27 Co
58.9
3
96 Cm
(247
)
64 Gd
157.
25
78 Pt19
5.08
46 Pd10
6.42
28 Ni
58.6
9
97 Bk
(247
)
65 Tb15
8.93
79 Au
196.
97
47 Ag
107.
87
29 Cu
63.5
5
The
Perio
dic
Tabl
e
Ato
mic
num
ber
Elem
ent
Rel
ativ
e at
omic
mas
s
98 Cf
(251
)
66 Dy
162.
50
80 Hg
200.
59
48 Cd
112.
41
30 Zn 65.3
8
99 Es (252
)
67 Ho
164.
93
81 Tl20
4.38
49 In11
4.82
31 Ga
69.7
2
13 Al
26.9
8
5 B10
.81
13
100
Fm (257
)
68 Er16
7.26
82 Pb 207.
2
50 Sn11
8.71
32 Ge
72.6
3
14 Si28
.09
6 C12
.01
14
101
Md
(258
)
69 Tm16
8.93
83 Bi
208.
98
51 Sb12
1.76
33 As
74.9
2
15 P30
.97
7 N14
.01
15
102
No
(259
)
70 Yb17
3.05
84 Po (209
)
52 Te12
7.60
34 Se78
.96
16 S32
.07
8 O16
.00
16
103
Lr (262
)
71 Lu17
4.97
85 At
(210
)
53 I12
6.90
35 Br
79.9
0
17 Cl
35.4
5
9 F19
.00
17
86 Rn
(222
)
54 Xe13
1.29
36 Kr
83.9
0
18 Ar
39.9
5
10 Ne
20.1
8
2 He
4.0018
34
56
78
910
1112
1 2 3 4 5 6 710
4 R
f(2
67)
105
Db
(268
)
106
Sg (269
)
107
Bh
(270
)
108
Hs
(269
)
109
Mt
(278
)
110
Ds
(281
)
111
Rg
(281
)
112
Cn
(285
)
113
Unt
(286
)
114
Uug
(289
)
115
Uup
(288
)
116
Uuh
(293
)
117
Uus
(294
)
118
Uuo
(294
)
– 2 – N17/4/CHEMI/SPM/ENG/TZ0/XX
1. How many atoms of nitrogen are there in 0.50 mol of (NH4)2CO3?
A. 1
B. 2
C. 3.01 × 1023
D. 6.02 × 1023
2. What is the value of x when 32.2 g of Na2SO4·xH2O are heated leaving 14.2 g of anhydrous Na2SO4? Mr (H2O) = 18; Mr (Na2SO4) = 142.
Na2SO4·xH2O (s) → Na2SO4 (s) + xH2O (g)
A. 0.1
B. 1
C. 5
D. 10
3. How many grams of sodium azide, NaN3, are needed to produce 68.1 dm3 of N2 (g) at STP?
Molar volume at STP = 22.7 dm3 mol-1; Mr (NaN3) = 65.0
2NaN3 (s) → 3N2 (g) + 2Na (s)
A. 32.5
B. 65.0
C. 130.0
D. 195.0
4. Whatisthesumofthecoefficientswhenthefollowingequationisbalancedusingthesmallestwholenumbers?
__C6H12O6(aq)→ __C2H5OH(aq)+ __CO2 (g)
A. 4
B. 5
C. 9
D. 10
Turn over
– 3 – N17/4/CHEMI/SPM/ENG/TZ0/XX
5. Whatisthenumberofprotonsandthenumberofneutronsin131I?
Protons Neutrons
A. 53 78
B. 53 131
C. 78 53
D. 131 53
6. Whichistheelectronconfigurationofachromiumatominthegroundstate?
A. [Ne]3s23p64s13d4
B. [Ar]3d3
C. 1s22s22p63s23p64s23d4
D. [Ar]4s13d5
7. Which trends are correct across period 3 (from Na to Cl)?
I. Atomic radius decreasesII. Melting point increasesIII. First ionization energy increases
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
– 4 – N17/4/CHEMI/SPM/ENG/TZ0/XX
8. WhichoxidedissolvesinwatertogiveasolutionwithapHbelow7?
A. MgO
B. Li2O
C. CaO
D. P4O10
9. The electronegativity values of four elements are given.
C N O F2.6 3.0 3.4 4.0
What is the order of increasing polarity of the bonds in the following compounds?
A. CO < OF2 < NO < CF4
B. CF4 < CO < OF2 < NO
C. NO < OF2 < CO < CF4
D. CF4 < NO < OF2 < CO
10. WhichcompoundhastheshortestC–Nbond?
A. CH3NH2
B. (CH3)3CNH2
C. CH3CN
D. CH3CHNH
Turn over
– 5 – N17/4/CHEMI/SPM/ENG/TZ0/XX
11. Whichofthefollowingseriesshowsincreasinghydrogenbondingwithwater?
A. Propane < propanal < propanol < propanoic acid
B. Propane < propanol < propanal < propanoic acid
C. Propanal < propane < propanoic acid < propanol
D. Propanoic acid < propanol < propanal < propane
12. Which statements are correct for metals?
I. Theyconductelectricitybecausetheyhavefreemovingions.II. They consist of a close-packed lattice of positive ions with delocalized electrons.III. Theyaremalleablebecausethelayersofpositiveionscanslideovereachother.
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
13. Which statement is correct for this reaction?
Fe2O3 (s) + 3CO (g) → 2Fe (s) + 3CO2(g)∆H = -26.6 kJ
A. 13.3 kJ are released for every mole of Fe produced.
B. 26.6kJareabsorbedforeverymoleofFeproduced.
C. 53.2 kJ are released for every mole of Fe produced.
D. 26.6 kJ are released for every mole of Fe produced.
– 6 – N17/4/CHEMI/SPM/ENG/TZ0/XX
14. The enthalpy changes for two reactions are given.
Br2 (l) + F2 (g) →2BrF(g)∆H = x kJBr2 (l) + 3F2 (g) → 2BrF3(g)∆H = y kJ
What is the enthalpy change for the following reaction?
BrF (g) + F2 (g) → BrF3 (g)
A. x - y
B. -x + y
C. 12
(-x + y)
D. 12
(x - y)
15. What is the enthalpy change, in kJ, of the following reaction?
3H2 (g) + N2 (g) � 2NH3 (g)
Bond Bond enthalpy / kJ mol-1
N≡N 945H-H 436N-H 391
A. (6 × 391) - [(3 × 436) + 945]
B. (3 × 391) - (436 + 945)
C. -[(3 × 436) + 945] + (3 × 391)
D. -(6 × 391) + [(3 × 436) + 945]
Turn over
– 7 – N17/4/CHEMI/SPM/ENG/TZ0/XX
16. Thediagramshowstheenergyprofileforacatalysedanduncatalysedreaction.Whichrepresentstheenthalpychange,∆H, and the activation energy, Ea, for the catalysed reaction?
x
y
zPote
ntia
l ene
rgy
Reaction coordinate
∆H Ea (catalysed reaction)
A. z x + z
B. z z + y
C. -z x
D. z + x x
– 8 – N17/4/CHEMI/SPM/ENG/TZ0/XX
17. Excessmagnesiumpowderwasaddedtoabeakercontaininghydrochloricacid,HCl(aq). Themassofthebeakeranditscontentswasrecordedandplottedagainsttime(lineI).
Mass
Time
I
II
Which change could give line II?
A. DoublingthemassofpowderedMg
B. UsingthesamemassofMgribbon
C. Increasing the temperature
D. Using the same volume of more concentrated HCl
18. Whatwillhappenifthepressureisincreasedinthefollowingreactionmixtureatequilibrium?
CO2 (g) + H2O (l) � H+(aq)+ HCO3-(aq)
A. TheequilibriumwillshifttotherightandpHwilldecrease.
B. TheequilibriumwillshifttotherightandpHwillincrease.
C. TheequilibriumwillshifttotheleftandpHwillincrease.
D. TheequilibriumwillshifttotheleftandpHwilldecrease.
Turn over
– 9 – N17/4/CHEMI/SPM/ENG/TZ0/XX
19. 10.0 cm3ofanaqueoussolutionofsodiumhydroxideofpH= 10 is mixed with 990.0 cm3 of distilled water. What is the pH of the resulting solution?
A. 8
B. 9
C. 11
D. 12
20. Which statement is incorrect for a 0.10 mol dm-3 HCOOH solution?
A. pH = 1
B. [H+ ] << 0.10 mol dm-3
C. [HCOO- ]isapproximatelyequalto[H+ ]
D. HCOOH is partially ionized
21. What are the oxidation states of chromium in (NH4)2Cr2O7 (s) and Cr2O3 (s)?
(NH4)2Cr2O7 (s) Cr2O3 (s)
A. +7 +3
B. +6 +3
C. +6 +6
D. +7 +6
22. Which of the following is a redox reaction?
A. 3Mg (s) + 2AlCl3(aq)→ 2Al (s) + 3MgCl2(aq)
B. SiO2 (s) +2NaOH(aq)→ Na2SiO3(aq)+ H2O (l)
C. KCl(aq)+ AgNO3(aq)→ AgCl (s) + KNO3(aq)
D. 2NaHCO3(aq)→ Na2CO3(aq)+ CO2 (g) + H2O (l)
– 10 – N17/4/CHEMI/SPM/ENG/TZ0/XX
23. What is the reaction type and major product at the anode (positive electrode) when molten sodium chloride is electrolysed using platinum electrodes?
Reaction type Product
A. reduction Cl2
B. oxidation Cl2
C. reduction Na
D. oxidation Na
24. WhatisthemajorproductofthereactionbetweenHClandbut-2-ene?
A. 1,2-dichlorobutane
B. 2,3-dichlorobutane
C. 1-chlorobutane
D. 2-chlorobutane
25. Whichcompoundcanbeoxidizedwhenheatedwithanacidifiedsolutionofpotassiumdichromate(VI)?
A. CH3C(O)CH2CH3
B. CH3CH2CH(OH)CH3
C. (CH3)3COH
D. CH3(CH2)2COOH
Turn over
– 11 – N17/4/CHEMI/SPM/ENG/TZ0/XX
26. What is the name of this compound, using IUPAC rules?
C
C
O
C
C
C HH
HH
HH
HHH
H
H H
A. 3-methylbutan-3-ol
B. 2-ethylpropan-2-ol
C. 2-methylbutan-2-ol
D. 3-methylbutan-2-ol
27. Whichtypeofreactionoccursbetweenanalcoholandacarboxylicacid?
A. Addition
B. Oxidation
C. Esterification
D. Polymerization
28. How many structural isomers of C6H14 exist?
A. 4
B. 5
C. 6
D. 7
– 12 – N17/4/CHEMI/SPM/ENG/TZ0/XX
29. Whatinformationisprovidedby1H NMR, MS and IR for an organic compound?
I. 1H NMR: chemical environment(s) of protonsII. MS: fragmentation patternIII. IR: types of functional group
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
30. Astudentperformsanacid-basetitrationusingapHmeter,butforgetstocalibrateit.Whichtypeoferrorwilloccurandhowwillitaffectthequalityofthemeasurements?
A. Random error and lower precision
B. Systematic error and lower accuracy
C. Systematic error and lower precision
D. Random error and lower accuracy
– 13 – N17/4/CHEMI/SPM/ENG/TZ0/XX
Candidate session number
12EP01
ChemistryStandard levelPaper 2
11 pages
Wednesday 8 November 2017 (afternoon)
1 hour 15 minutes
N17/4/CHEMI/SP2/ENG/TZ0/XX
© International Baccalaureate Organization 20178817 – 6105
Instructions to candidates
Write your session number in the boxes above. Do not open this examination paper until instructed to do so. Answer all questions. Write your answers in the boxes provided. A calculator is required for this paper. A clean copy of the chemistry data booklet is required for this paper. The maximum mark for this examination paper is [50 marks].
Answer all questions. Write your answers in the boxes provided.
1. A student titrated an ethanoic acid solution, CH3COOH (aq), against 50.0 cm3 of 0.995 mol dm-3 sodium hydroxide, NaOH (aq), to determine its concentration. The temperature of the reaction mixture was measured after each acid addition and plotted against the volume of acid.
5 10 15 20 25 30 35 40 45 500
20
21
22
23
24
25
26
27
28
29
30
31
32
Tem
pera
ture
/ °C
Volume of acid / cm3
(a) Using the graph, estimate the initial temperature of the solution. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(This question continues on the following page)
12EP02
– 2 – N17/4/CHEMI/SP2/ENG/TZ0/XX
(Question 1 continued)
(b) Determine the maximum temperature reached in the experiment by analysing the graph. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(c) Calculate the concentration of ethanoic acid, CH3COOH, in mol dm-3. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(d) (i) Determine the heat change, q , in kJ, for the neutralization reaction between ethanoic acid and sodium hydroxide.Assume the specific heat capacities of the solutions and their densities are those of water. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(ii) Calculate the enthalpy change, ∆H, in kJ mol-1, for the reaction between ethanoic acid and sodium hydroxide. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(This question continues on the following page)
12EP03
Turn over
– 3 – N17/4/CHEMI/SP2/ENG/TZ0/XX
(Question 1 continued)
(e) Curves X and Y were obtained when a metal carbonate reacted with the same volume of ethanoic acid under two different conditions.
X
Y
Volu
me
of g
as
Time
(i) Explain the shape of curve X in terms of the collision theory. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(ii) Suggest one possible reason for the differences between curves X and Y. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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12EP04
– 4 – N17/4/CHEMI/SP2/ENG/TZ0/XX
2. Trends in physical and chemical properties are useful to chemists.
(a) Explain the general increasing trend in the first ionization energies of the period 3 elements, Na to Ar. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(b) Explain why the melting points of the group 1 metals (Li → Cs) decrease down the group. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(c) State an equation for the reaction of phosphorus(V) oxide, P4O10 (s), with water. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(d) Describe the emission spectrum of hydrogen. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(This question continues on the following page)
12EP05
Turn over
– 5 – N17/4/CHEMI/SP2/ENG/TZ0/XX
(Question 2 continued)
(e) The Activity series lists the metal in order of reactivity.
Mn Most reactive
Least reactiveNiAg
(i) Identify the strongest reducing agent in the given list. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(ii) A voltaic cell is made up of a Mn2+/Mn half-cell and a Ni2+/Ni half-cell. Deduce the equation for the cell reaction. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(iii) The voltaic cell stated in part (ii) is partially shown below.Draw and label the connections needed to show the direction of electron movement and ion flow between the two half-cells. [2]
Ni (s)
Ni2+ (aq) Mn2+ (aq)
Mn (s)
12EP06
– 6 – N17/4/CHEMI/SP2/ENG/TZ0/XX
3. Lewis (electron dot) structures are useful models.
(a) Draw the Lewis (electron dot) structures of PF3 and PF4+ and use the VSEPR theory to
deduce the molecular geometry of each species.
PF3 PF4+
Lewis (electron dot) structure
Molecular geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
[4]
(b) Predict with a reason, whether the molecule PF3 is polar or non-polar. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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4. Menthol is an organic compound containing carbon, hydrogen and oxygen.
(a) Complete combustion of 0.1595 g of menthol produces 0.4490 g of carbon dioxide and 0.1840 g of water. Determine the empirical formula of the compound showing your working. [3]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(This question continues on the following page)
12EP07
Turn over
– 7 – N17/4/CHEMI/SP2/ENG/TZ0/XX
(Question 4 continued)
(b) 0.150 g sample of menthol, when vaporized, had a volume of 0.0337 dm3 at 150 °C and 100.2 kPa. Calculate its molar mass showing your working. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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5. Many reactions are in a state of equilibrium.
(a) The following reaction was allowed to reach equilibrium at 761 K.
H2 (g) + I2 (g) 2HI (g) ∆H Ö < 0
Outline the effect, if any, of each of the following changes on the position of equilibrium, giving a reason in each case.
Effect Reason
Increasing the volume, at constant temperature
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Increasing the temperature, at constant pressure
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[2]
(b) The equations for two acid-base reactions are given below.
HCO3– (aq) + H2O (l) H2CO3 (aq) + OH– (aq)
HCO3– (aq) + H2O (l) CO3
2– (aq) + H3O+ (aq)
(i) Identify two different amphiprotic species in the above reactions. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(This question continues on the following page)
12EP08
– 8 – N17/4/CHEMI/SP2/ENG/TZ0/XX
(Question 5 continued)
(ii) State what is meant by the term conjugate base. [1]
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(iii) State the conjugate base of the hydroxide ion, OH–. [1]
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(c) A student working in the laboratory classified HNO3, H2SO4, H3PO4 and HClO4 as acids based on their pH. He hypothesized that “all acids contain oxygen and hydrogen”. Evaluate his hypothesis. [2]
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12EP09
Turn over
– 9 – N17/4/CHEMI/SP2/ENG/TZ0/XX
6. The reactivity of organic compounds depends on the nature and positions of their functional groups.
(a) The structural formulas of two organic compounds are shown below.
H C C CH3
CH3COOH
OH H
H C C CH3
CH3COOH
H OH
A B
(i) Deduce the type of chemical reaction and the reagents used to distinguish between these compounds. [1]
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(ii) State the observation expected for each reaction giving your reasons. [2]
Compound A:
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Compound B:
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(This question continues on the following page)
12EP10
– 10 – N17/4/CHEMI/SP2/ENG/TZ0/XX
(Question 6 continued)
(iii) Deduce the number of signals and the ratio of areas under the signals in the 1H NMR spectra of the two compounds.
Compound Number of signals Ratio of areas
A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
[4]
(b) Explain, with the help of equations, the mechanism of the free-radical substitution reaction of ethane with bromine in presence of sunlight. [4]
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12EP11
– 11 – N17/4/CHEMI/SP2/ENG/TZ0/XX
Please do not write on this page.
Answers written on this page will not be marked.
12EP12
Please do not write on this page.
Answers written on this page will not be marked.
N17
/4/C
HEM
I/SP2
/EN
G/T
Z0/X
X/M
13 p
ages
Mar
ksch
eme
Nov
embe
r 201
7
Che
mis
try
Stan
dard
leve
l
Pape
r 2
–2
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
This
mar
ksch
eme
is th
e pr
oper
ty o
f the
Inte
rnat
iona
l Ba
ccal
aure
ate
and
mus
t not
be
repr
oduc
ed o
r dis
tribu
ted
to a
ny
othe
r per
son
with
out t
he a
utho
rizat
ion
of th
e IB
Glo
bal C
entre
, C
ardi
ff.
– 3
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
1.
a
21.4
°C ✔
Acc
ept v
alue
s in
the
rang
e of
21.
2 to
21
.6 °C
.
1
–4
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
1.
b 29
.0 «
°C» ✔
Acc
ept r
ange
28.
8 to
29.
2 °C
. 1
1.
c A
LTER
NA
TIVE
1
«vol
ume
CH
3CO
OH
=»
26.0
«cm
3 » ✔
«[C
H3C
OO
H] =
0.9
95 m
ol d
m–3
3 3
50.0
cm
26.0
cm=»
1.9
1 «m
ol d
m−3
» ✔
ALT
ERN
ATI
VE 2
«n(N
aOH
) =0.
995
mol
dm
-3
0.0
500
dm3 =
» 0.
0497
5 «m
ol» ✔
«[C
H3C
OO
H] =
3
0.04
975
dm0.
0260
=»
1.91
«m
ol d
m-3
» ✔
Acc
ept v
alue
s of
vol
ume
in ra
nge
25.5
to 2
6.5
cm3 .
Aw
ard
[2] f
or c
orre
ct fi
nal a
nsw
er.
2
1.
d i
«tot
al v
olum
e
50.0
2
6.0 »
76.
0 cm
3 AN
D «
tem
pera
ture
cha
nge
29.0
2
1.4 »
7.
6 «°
C» ✔
«q
0.0
760
kg
4.1
8 kJ
kg–1
K–1
7
.6 K
»
2.4
«kJ»
✔
Aw
ard
[2] f
or c
orre
ct fi
nal a
nsw
er.
2
– 5
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l 1.
d
ii «n
(NaO
H)
0.9
95 m
ol d
m-3
0
.050
0 dm
3 »
0.04
975
«mol
» O
R
«n(C
H3C
OO
H)
1.9
1 m
ol d
m-3
0
.026
0 dm
3 »
0.04
966
«mol
» ✔
«H
2.4
kJ0.
0497
5m
ol
»
48 /
49 «
kJ m
ol–1
» ✔
Aw
ard
[2] f
or c
orre
ct fi
nal a
nsw
er.
Neg
ativ
e si
gn is
requ
ired
for M
2.
2
1.
e i
«ini
tially
ste
ep b
ecau
se»
grea
test
con
cent
ratio
n/nu
mbe
r of p
artic
les
at s
tart
OR
«slo
pe d
ecre
ases
bec
ause
» co
ncen
tratio
n/nu
mbe
r of p
artic
les
decr
ease
s ✔
volu
me
prod
uced
per
uni
t of t
ime
depe
nds
on fr
eque
ncy
of c
ollis
ions
O
R
rate
dep
ends
on
frequ
ency
of c
ollis
ions
✔
2
1.
e ii
mas
s/am
ount
/con
cent
ratio
n of
met
al c
arbo
nate
mor
e in
X
OR
conc
entra
tion/
amou
nt o
f CH
3CO
OH
mor
e in
X ✔
1
– 6
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
2.
a in
crea
sing
num
ber o
f pro
tons
O
R
incr
easi
ng n
ucle
ar c
harg
e ✔
«ato
mic
» ra
dius
/siz
e de
crea
ses
OR
sa
me
num
ber o
f she
lls
OR
sim
ilar s
hiel
ding
«by
inne
r ele
ctro
ns» ✔
«gre
ater
ene
rgy
need
ed to
ove
rcom
e in
crea
sed
attra
ctio
n be
twee
n nu
cleu
s an
d el
ectro
ns»
2
2.
b at
omic
/ioni
c ra
dius
incr
ease
s ✔
smal
ler c
harg
e de
nsity
OR
forc
e of
attr
actio
n be
twee
n m
etal
ions
and
del
ocal
ised
ele
ctro
ns d
ecre
ases
✔
Do
not a
ccep
t dis
cuss
ion
of a
ttrac
tion
betw
een
vale
nce
elec
trons
and
nu
cleu
s fo
r M2.
A
ccep
t “w
eake
r met
allic
bon
ds” f
or M
2.
2
2.
c P 4
O10
(s)
6H
2O (l
)
4H
3PO
4 (a
q) ✔
Acc
ept “
P4O
10 (s
) 2
H2O
(l)
4HP
O3(
aq)”
(ini
tial r
eact
ion)
. 1
2.
d «s
erie
s of
» lin
es
OR
only
cer
tain
freq
uenc
ies/
wav
elen
gths
✔
conv
erge
nce
at h
igh«
er»
frequ
ency
/ene
rgy/
shor
t«er
» w
avel
engt
h ✔
M1
and/
or M
2 m
ay b
e sh
own
on a
di
agra
m.
2
– 7
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
2.
e i
Mn ✔
1
2.
e ii
Mn(
s)
Ni2+
(aq)
N
i(s)
Mn2+
(aq)
✔1
2.
e iii
w
ire b
etw
een
elec
trode
s A
ND
labe
lled
salt
brid
ge in
con
tact
with
bot
h el
ectro
lyte
s ✔
anio
ns to
righ
t (sa
lt br
idge
) O
R
catio
ns to
left
(sal
t brid
ge)
OR
ar
row
from
Mn
to N
i (on
wire
or n
ext t
o it)
✔
Ele
ctro
des
can
be c
onne
cted
dire
ctly
or
thro
ugh
voltm
eter
/am
met
er/li
ght b
ulb,
bu
t not
a b
atte
ry/p
ower
sup
ply.
A
ccep
t ion
s or
a s
peci
fic s
alt a
s th
e la
bel o
f the
sal
t brid
ge.
2
– 8
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
3.
a PF
3PF
4+
Lew
is
stru
ctur
e ✔
✔
Mol
ecul
ar
geom
etry
tri
gona
l pyr
amid
al ✔
tetra
hedr
al ✔
Acc
ept a
ny c
ombi
natio
n of
dot
s,
cros
ses
and
lines
. Ig
nore
mis
sing
bra
cket
s an
d po
sitiv
e ch
arge
.
Pen
aliz
e m
issi
ng lo
ne p
airs
onc
e on
ly.
Do
not a
pply
EC
F fo
r mol
ecul
ar
geom
etry
. 4
3.
b po
lar A
ND
bon
d po
larit
ies/
dipo
les
do n
ot c
ance
l out
O
R
pola
r AN
D u
nsym
met
rical
dis
tribu
tion
of c
harg
e ✔
App
ly E
CF
from
par
t (a)
mol
ecul
ar
geom
etry
. 1
– 9
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
4.
a ca
rbon
: «–1
0.44
90 g
44.0
1 g
mol
»
0.01
020
«mol
» / 0
.122
5 «g
»
OR
hydr
ogen
: «0.
1840
218
.02
»
0.02
042
«mol
» / 0
.020
6 «g
» ✔
oxyg
en: «
0.15
95 –
(0.1
225
0.02
06)»
0
.016
4 «g
» / 0
.001
025
«mol
» ✔
empi
rical
form
ula:
C10
H20
O ✔
Aw
ard
[3] f
or c
orre
ct fi
nal a
nsw
er.
3
4.
b te
mpe
ratu
re
423
K
OR
M =
mR
TpV
✔
«M =
–1–1
30.
150
g 8
.31J
Km
ol42
3K
100.
2kP
a0.
0337
dm»
156
«g
mol
–1» ✔
Aw
ard
[1] f
or c
orre
ct a
nsw
er w
ith n
o w
orki
ng s
how
n.
Acc
ept “
pV =
nR
T A
ND
n =
m M” f
or M
1.
2
– 10
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
5.
a Ef
fect
R
easo
n In
crea
sing
the
volu
me,
at
cons
tant
tem
pera
ture
no
ne/n
o ef
fect
A
ND
sa
me
num
ber o
f «ga
s»
mol
es/m
olec
ules
on
both
si
des ✔
Incr
easi
ng th
e te
mpe
ratu
re, a
t con
stan
t pr
essu
re
mov
es to
left
A
ND
«f
orw
ard»
reac
tion
is
exot
herm
ic ✔
Aw
ard
[1 m
ax] i
f bot
h ef
fect
s ar
e co
rrec
t.
Rea
son
for i
ncre
asin
g vo
lum
e:
Acc
ept “
conc
entra
tion
of a
ll re
agen
ts
redu
ced
by a
n eq
ual a
mou
nt s
o ca
ncel
s ou
t in
Kc e
xpre
ssio
n”.
Acc
ept “
affe
cts
both
forw
ard
and
back
war
d ra
tes
equa
lly”.
2
5.
b i
HC
O3– A
ND
H2O
✔1
5.
b ii
spec
ies
that
has
one
less
pro
ton/
H i
on «
than
its
conj
ugat
e ac
id»
OR
sp
ecie
s th
at fo
rms
its c
onju
gate
aci
d by
acc
eptin
g a
prot
on
OR
spec
ies
that
is fo
rmed
whe
n an
aci
d do
nate
s a
prot
on ✔
Do
not a
ccep
t “di
ffers
by
one
prot
on/H
+ fro
m c
onju
gate
aci
d”.
1
5.
b iii
ox
ide
ion/
O2–
✔1
– 11
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
5.
c in
suffi
cien
t dat
a to
mak
e ge
nera
lizat
ion
OR
ne
ed to
con
side
r a «
muc
h» la
rger
num
ber o
f aci
ds
OR
hy
poth
esis
will
cont
inue
to b
e te
sted
with
new
aci
ds to
see
if it
can
sta
nd th
e te
st
of ti
me ✔
«hyp
othe
sis
is fa
lse
as»
othe
r aci
ds/H
Cl/H
Br/H
CN
/tran
sitio
n m
etal
ion/
BF3 d
o no
t co
ntai
n ox
ygen
O
R
othe
r aci
ds/H
Cl/H
Br/H
CN
/tran
sitio
n m
etal
ion/
BF3 f
alsi
fy h
ypot
hesi
s ✔
corre
ct in
duct
ive
reas
onin
g «b
ased
on
limite
d sa
mpl
e» ✔
«hyp
othe
sis
not v
alid
as»
it c
ontra
dict
s cu
rrent
/acc
epte
d th
eorie
s/Br
ønst
ed-
Low
ry/L
ewis
theo
ry ✔
2 m
ax
– 12
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
6.
a i
oxid
atio
n/re
dox
AN
D a
cidi
fied
«pot
assi
um»
dich
rom
ate(
VI)
OR
oxid
atio
n/re
dox
AN
D «
acid
ified
pot
assi
um»
man
gana
te(V
II) ✔
Acc
ept “
acid
ified
«po
tass
ium
» di
chro
mat
e” O
R “«
acid
ified
pot
assi
um»
perm
anga
nate
”.
Acc
ept n
ame
or fo
rmul
a of
the
reag
ent(s
).
1
6.
a ii
ALT
ERN
ATI
VE 1
usi
ng K
2Cr 2
O7:
Com
poun
d A
: ora
nge
to g
reen
AN
D s
econ
dary
hyd
roxy
l O
R
Com
poun
d A
: ora
nge
to g
reen
AN
D h
ydro
xyl o
xidi
zed
«by
chro
miu
m(V
I) io
ns» ✔
Com
poun
d B
: no
chan
ge A
ND
terti
ary
hydr
oxyl
«no
t oxi
dize
d by
chr
omiu
m(V
I) io
ns» ✔
ALT
ERN
ATI
VE 2
usi
ng K
MnO
4: C
ompo
und
A: p
urpl
e to
col
ourle
ss A
ND
sec
onda
ry h
ydro
xyl
OR
C
ompo
und
A: p
urpl
e to
col
ourle
ss A
ND
hyd
roxy
l oxi
dize
d «b
y m
anga
nese
(VII)
io
ns» ✔
Com
poun
d B
: no
chan
ge A
ND
terti
ary
hydr
oxyl
«no
t oxi
dize
d by
man
gane
se(V
II)
ions
» ✔
Aw
ard
[1] f
or “A
: ora
nge
to g
reen
AN
D
B: n
o ch
ange
”.
Aw
ard
[1] f
or “A
: sec
onda
ry h
ydro
xyl
AN
D B
: ter
tiary
hyd
roxy
l”.
Acc
ept “
alco
hol”
for “
hydr
oxyl
”.
Aw
ard
[1] f
or “A
: pur
ple
to c
olou
rless
A
ND
B: n
o ch
ange
”
Aw
ard
[1] f
or “A
: sec
onda
ry h
ydro
xyl
AN
D B
: ter
tiary
hyd
roxy
l”.
Acc
ept “
purp
le to
bro
wn”
for A
.
2
6.
a iii
C
ompo
und
Num
ber o
f sig
nals
R
atio
of a
reas
A
5 ✔
6:1:
1:1:
1✔
B
4 ✔
6:1:
1:2
✔
Acc
ept r
atio
of a
reas
in a
ny o
rder
. D
o no
t app
ly E
CF
for r
atio
s.
4
– 13
–N
17/4
/CH
EMI/S
P2/E
NG
/TZ0
/XX/
M
Que
stio
n A
nsw
ers
Not
es
Tota
l
6.
b In
itiat
ion:
Br2
UV
//
hvhe
at
2Br
• ✔
Pro
paga
tion:
Br•
C2H
6
C2H
5•
HBr
✔
C2H
5•
Br 2
C
2H5B
r B
r• ✔
Term
inat
ion:
Br
• B
r•
Br 2
OR
C2H
5•
Br•
C
2H5B
r
OR
C2H
5•
C2H
5•
C4H
10 ✔
Ref
eren
ce to
UV
/hν/
heat
not
requ
ired.
Acc
ept r
epre
sent
atio
n of
radi
cal w
ithou
t •(
eg, B
r, C
2H5)
if c
onsi
sten
t thr
ough
out
mec
hani
sm.
Acc
ept f
urth
er b
rom
inat
ion.
Aw
ard
[3 m
ax] i
f ini
tiatio
n, p
ropa
gatio
n an
d te
rmin
atio
n ar
e no
t sta
ted
or a
re
inco
rrec
tly la
belle
d fo
r equ
atio
ns.
Aw
ard
[3 m
ax] i
f met
hane
is u
sed
inst
ead
of e
than
e, a
nd/o
r chl
orin
e is
us
ed in
stea
d of
bro
min
e.
4
Candidate session number
ChemistryStandard levelPaper 3
27 pages
Thursday 9 November 2017 (morning)
1 hour
28EP01
N17/4/CHEMI/SP3/ENG/TZ0/XX
© International Baccalaureate Organization 20178817 – 6106
Instructions to candidates
• Write your session number in the boxes above.• Do not open this examination paper until instructed to do so.• Answers must be written within the answer boxes provided.• A calculator is required for this paper.• A clean copy of the chemistry data booklet is required for this paper.• The maximum mark for this examination paper is [35 marks].
Section A QuestionsAnswer all questions. 1 – 3
Section B QuestionsAnswer all of the questions from one of the options.
Option A — Materials 4 – 7
Option B — Biochemistry 8 – 11
Option C — Energy 12 – 15
Option D — Medicinal chemistry 16 – 21
Please do not write on this page.
Answers written on this page will not be marked.
28EP02
– 2 – N17/4/CHEMI/SP3/ENG/TZ0/XX
Section A
Answer all questions. Write your answers in the boxes provided.
1. A student set up a simple voltaic cell consisting of a copper electrode and a zinc electrode dipped in sodium chloride solution.
d
Ammeter
NaCl (aq)
Cu Zn
The student gradually increased the distance, d,betweentheelectrodestostudytheeffecton the initial current, I, passing through the light bulb.
The student hypothesized that the initial current would be inversely proportional to the distance between the electrodes.
(a) Sketch a graph that would support the student’s hypothesis. [1]
(This question continues on the following page)
Turn over
28EP03
– 3 – N 17 / 4 /CHEMI/S P 3/ ENG /TZ0 / XX
(Question 1 continued)
(b) Thefollowingdatawascollectedoverfivetrials.
d / ±0.1 cm Average I / ±0.04 A4.0 0.093
10.0 0.08316.0 0.07320.0 0.06726.0 0.057
The data did not support the student’s hypothesis. He investigated other possible relationships by plotting a graph of the average current against the distance between theelectrodes.Heobtainedthefollowingbest-fitlinewithacorrelationcoefficient(r)of −0.9999.
0.10
0.05
0.000 10 20
d / cm
I / A
Linearfitfordatasety =m x + bm (Slope): −0.001631 A cm−1
b ( y-intercept): 0.09939 ACorrelation: −0.9999
(i) Suggestwhatthecorrelationcoefficientof−0.9999 indicates. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(This question continues on the following page)
28EP04
– 4 – N17/4/CHEMI/SP3/ENG/TZ0/XX
(Question 1 continued)
(ii) State the equation of the straight line obtained using the data. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(iii) Outlinehowcurrentflowsinthesodiumchloridesolution. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turn over
28EP05
– 5 – N17/4/CHEMI/SP3/ENG/TZ0/XX
2. Antacids react with hydrochloric acid in the stomach to relieve indigestion. A student investigateddifferentbrandsofantacidtoseewhichcausedthelargestincreaseinpHina given time. She added the antacids to hydrochloric acid, and recorded the change in pH overfiveminutes.
Antacid brand
Active ingredient(s) Recommended dosage
Dose used
Initial pH ±0.02
Final pH ±0.02
Change in pH
A magnesium hydroxidealuminium hydroxide
2–3tablets
2tablets
1.68 4.53 +2.85
B sodium hydrogen carbonatecalcium carbonate
2–4tablets
2tablets
1.70 5.31 +3.61
C calcium carbonate 1–2tablets
1tablet
1.70 4.52 +2.82
D magnesium hydroxidealuminium oxidealuminium hydroxide
1–2tablets
1tablet
1.69 2.21 +0.52
(a) State an equation for the reaction of magnesium hydroxide with hydrochloric acid. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(This question continues on the following page)
28EP06
– 6 – N17/4/CHEMI/SP3/ENG/TZ0/XX
(Question 2 continued)
(b) Suggest two variables, besides the time of reaction, which the student should have controlled in the experiment to ensure a fair comparison of the antacids. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(c) Calculate the uncertainty in the change in pH. [1]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(d) The student concluded that antacid Bwasthemosteffective,followedbyA then C and finallyD. Discuss two arguments that reduce the validity of the conclusion. [2]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turn over
28EP07
– 7 – N17/4/CHEMI/SP3/ENG/TZ0/XX
3. Sodium chloride, NaCl, can be spread on icy roads to lower the freezing point of water. ThediagramshowstheeffectsoftemperatureandpercentagebymassofNaCl on the composition of a mixture of NaCl and H2O.
10 20 30 40 500
–30
–20
–10
10
20
30
40
0101010 202020 303030 404040 5050404030302020101010 20 30 40 5050404030302020101010 20 30 40
Tem
pera
ture
/ °C
Percentage of NaCl by mass / %
ice + NaCl (aq)
ice + NaCl·2H2O (s)
NaCl (aq) NaCl (aq) + NaCl·2H2O (s)
(a) Estimate the lowest freezing point of water that can be reached by adding sodium chloride. [1]
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(b) Estimate the percentage by mass of NaCl dissolved in a saturated sodium chloride solution at +10 ûC. [1]
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(This question continues on the following page)
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(Question 3 continued)
(c) Calculate the percentage of water by mass in the NaCl·2H2O crystals. Use the data from section 6 of the data booklet and give your answer to two decimal places. [2]
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(d) Suggest a concern about spreading sodium chloride on roads. [1]
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Section B
Answer all of the questions from one of the options. Write your answers in the boxes provided.
Option A — Materials
4. Itiswisetofilldentalcavitiesbeforeirreversibletoothdecaysetsin.Anamalgam(alloyof mercury, silver, and other metals) is often used although many prefer a white composite material.
(a) Outline the composition of an alloy and a composite. [2]
Alloy:
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Composite:
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(b) (i) Outline why an alloy is usually harder than its components by referring to its structure. [1]
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(ii) Atpresent,compositefillingsaremoreexpensivethanamalgamfillings. Suggestwhyapatientmightchooseacompositefilling. [1]
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(Option A continues on the following page)
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(Option A, question 4 continued)
(c) Explain how Inductively Coupled Plasma (ICP) Spectroscopy could be used to determinetheconcentrationofmercuryinasampleofdentalfilling. [3]
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5. Catalysts can take many forms and are used in many industrial processes.
Suggest two reasons why it might be worth using a more expensive catalyst to increase the rate of a reaction. [2]
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(Option A continues on the following page)
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(Option A continued)
6. Nanotechnology has many applications.
(a) State equations for the formation of iron nanoparticles and carbon atoms from Fe(CO)5 in the HIPCO process. [2]
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(b) Outline why the iron nanoparticle catalysts produced by the HIPCO process are more efficientthansolidironcatalysts. [1]
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(c) Discuss one possible risk associated with the use of nanotechnology. [1]
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(Option A continues on the following page)
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(Option A continued)
7. The development of materials with unique properties is critical to advances in industry.
(a) Outline two properties a substance should have to be used as liquid-crystal in a liquid-crystal display. [2]
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(b) Low density polyethene (LDPE) and high density polyethene (HDPE) are both addition polymers.
(i) DescribehowthestructuresofLDPEandHDPEaffectonemechanicalpropertyof the plastics. [2]
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(Option A continues on the following page)
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(Option A, question 7 continued)
(ii) One of the two infrared (IR) spectra is that of polyethene and the other of polytetrafluoroethene(PTFE).
(Option A continues on the following page)
Removed for copyright reasons
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(Option A, question 7 continued)
Deduce, with a reason, which spectrum is that of PTFE. Infrared data is given in section 26 of the data booklet. [1]
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(c) Many plastics used to be incinerated. Deduce an equation for the complete combustion of two repeating units of PVC, (−C2H3Cl−)2. [2]
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End of Option A
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Option B — Biochemistry
8. Consider the following lipid and carbohydrate.
CH3(CH2)4(CH=CHCH2)2(CH2)6COOH
CH2OH
H
OH H
OH
CH2OH
OHHO
Linoleic acid, Mr = 280.50 Fructose, Mr = 180.18
(a) (i) Determine the empirical formula of linoleic acid. [1]
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(ii) The empirical formula of fructose is CH2O. Suggest why linoleic acid releases more energy per gram than fructose. [1]
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(b) In order to determine the number of carbon-carbon double bonds in a molecule of linoleic acid, 1.24 g of the lipid were dissolved in 10.0 cm3 of non-polar solvent. The solution was titrated with a 0.300 mol dm−3 solution of iodine, I2 .
(i) State the type of reaction occurring during the titration. [1]
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(Option B continues on the following page)
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(Option B, question 8 continued)
(ii) Calculate the volume of iodine solution used to reach the end-point. [3]
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(c) Outline the importance of linoleic acid for human health. [2]
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(Option B continues on the following page)
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(Option B continued)
9. Lactose is a disaccharide formed by the condensation reaction of the monosaccharides galactose and glucose.
OOH
H H
O
OH H
OH
H OH
H OH
CH2OH
CH2OH
H
OH H
H
OH H
Lactose
(a) Describe what is meant by a condensation reaction. [2]
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(b) Draw the structure of galactose on the skeleton provided. [1]
O
(Option B continues on the following page)
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(Option B, question 9 continued)
(c) Explain how the inclusion of carbohydrates in plastics makes them biodegradable. [2]
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10. Vitamins can be water-soluble or fat-soluble.
(a) Explain, at the molecular level, why vitamin D is soluble in fats. Use section 35 of the data booklet. [2]
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(b) State one function of vitamin D in the body. [1]
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(Option B continues on the following page)
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(Option B continued)
11. Enzyme activity depends on many factors. Explain how pH change causes loss of activity of an enzyme. [4]
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End of Option B
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Option C — Energy
12. Onemethodofcomparingfuelsisbyconsideringtheirspecificenergies.
(a) Calculatethespecificenergyofoctane,C8H18 , in kJ kg–1 using sections 1, 6 and 13 of the data booklet. [2]
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(b) Atypicalwoodhasaspecificenergyof17× 103 kJ kg–1. Comment on the usefulness of octane and wood for powering a moving vehicle, using your answer to (a).If you did not work out an answer for (a), use 45 × 103 kJ kg–1 but this is not the correct answer. [1]
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(c) State the name of one renewable source of energy other than wood. [1]
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(Option C continues on the following page)
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(Option C continued)
13. Muchofourenergyneedsarestillprovidedbytherefinedproductsofcrudeoil.
(a) “Knocking” in an automobile (car) engine can be prevented by increasing the octane number of the fuel. Explain, including an equation with structural formulas, how heptane, C7H16 , could be chemically converted to increase its octane number. [3]
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(b) Manyliketorefertoour“carbonfootprint”.Outlineonedifficultyinquantifyingsuchaconcept. [1]
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(c) Climate change or global warming is a consequence of increased levels of carbon dioxideintheatmosphere.Explainhowthegreenhouseeffectwarmsthesurfaceofthe earth. [3]
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(Option C continues on the following page)
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(Option C, question 13 continued)
(d) Outline how water and carbon dioxide absorb infrared radiation. [1]
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14. Inthe20thCentury,bothfissionandfusionwereconsideredassourcesofenergybutfusionwaseconomically and technically unattainable.
(a) (i) Compareandcontrastfissionandfusionintermsofbindingenergyandthetypesof nuclei involved. [2]
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(ii) Suggest twoadvantagesthatfusionhasoverfission. [2]
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(b) The amount of 228Ac in a sample decreases to one eighth of its original value in
about 18 hours due to β-decay. Estimate the half-life of 228Ac. [1]
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(Option C continues on the following page)
18( (
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(Option C continued)
15. Vegetable oils can be used as a source of energy.
(a) State the structural feature of chlorophyll that enables it to absorb visible light. [1]
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(b) Vegetable oils are too viscous for use as liquid fuels. Describe, using an equation, how a vegetable oil, such as that shown, is converted to oils with lower viscosity by reaction with methanol, CH3OH. [2]
O
H2C O C (CH2)6CH3O
HC O C (CH2)6CH3O
H2C O C (CH2)6CH3
End of Option C
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Option D — Medicinal chemistry
16. Radioisotopes are used to diagnose and treat various diseases. Explain the low environmental impact of most medical nuclear waste. [2]
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17. Some analgesics are derived from compounds found in plants.
(a) Aspirin is a mild analgesic derived from salicylic acid found in willow bark.Describe how mild analgesics function. [2]
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(b) (i) The strong analgesics morphine and codeine are opiates. Outline how codeine can be synthesized from morphine. The structures of morphine and codeine are in section 37 of the data booklet. [1]
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(ii) Explain why opiates are addictive. [2]
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(Option D continues on the following page)
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(Option D continued)
18. New drugs undergo thorough clinical trials before they are approved.
(a) Outlinethedifferencebetweenthetherapeuticindexinanimalstudiesandthetherapeutic index in humans. [1]
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(b) State the method of drug administration that gives the maximum bioavailability. [1]
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19. Oseltamivir(Tamiflu)andzanamivir(Relenza)areantiviraldrugsusedtopreventflu.
(a) State the names of two functional groups that both compounds contain, using section 37 of the data booklet. [2]
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(b) Explainhowoseltamivirandzanamivircanstopthespreadofthefluvirusinthebody. [2]
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(Option D continues on the following page)
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(Option D continued)
20. Excess acid in the stomach can cause discomfort and more serious health issues.
(a) Explain how ranitidine (Zantac) reduces stomach acid production. [2]
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(b) ThepHismaintainedindifferentfluidsinthebodybytheuseofbuffers.
CalculatethepHofabuffersolutionof0.0200moldm−3 carbonic acid, H2CO3 , and 0.400 mol dm−3 sodium hydrogen carbonate, NaHCO3 . The pKa of carbonic acid is 6.35. [2]
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21. Molecules of antibiotics often contain a beta-lactam ring. Explain the importance of the beta-lactam ring in the action of penicillin, using section 37 of the data booklet. [3]
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End of Option D
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– 27 – N17/4/CHEMI/SP3/ENG/TZ0/XX
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