ChemHL P2 M06 TZ0 - IB DIPLOMA PROGRAMME PROGRAMME DU...

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Unformatted text preview: IB DIPLOMA PROGRAMME PROGRAMME DU DIPLME DU BI PROGRAMA DEL DIPLOMA DEL BI M06/4/CHEMI/HP2/ENG/TZ0/XX 22066102 CHEMISTRY HIGHER LEVEL PAPER 2 Thursday 18 May 2006 (afternoon) 2 hours 15 minutes INSTRUCTIONS TO CANDIDATES Write your session number in the boxes above. Do not open this examination paper until instructed to do so. Section A: answer all of Section A in the spaces provided. Section B: answer two questions from Section B. Write your answers on answer sheets. Write your session number on each answer sheet, and attach them to this examination paper and your cover sheet using the tag provided. At the end of the examination, indicate the numbers of the questions answered in the candidate box on your cover sheet and indicate the number of sheets used in the appropriate box on your cover sheet. Candidate session number 0 0 2206-6102 12 pages 0112 2 SECTION A Answer all the questions in the spaces provided. 1. M06/4/CHEMI/HP2/ENG/TZ0/XX Hex-1-ene gas, C6 H12, burns in oxygen to produce carbon dioxide and water vapour. (a) Write an equation to represent this reaction. ...................................................................... (b) Use the data below to calculate the values of H cV and ScV for the combustion of hex-1-ene. Substance Standard enthalpy of formation, H f 0 / kJ mol -1 Entropy, S0 / J K -1 mol -1 (i) Value of H cV ................................................................. ................................................................. ................................................................. ................................................................. (ii) Value of ScV ................................................................. ................................................................. ................................................................. ................................................................. (c) Calculate the standard free energy change for the combustion of hex-1-ene. ...................................................................... ...................................................................... ...................................................................... ...................................................................... [2] [2] O 2 (g) 0.0 205 C6 H12 (g) 43 385 CO 2 (g) 394 214 H 2 O(g) 242 189 [2] [1] (This question continues on the following page) 2206-6102 0212 3 (Question 1 continued) (d) M06/4/CHEMI/HP2/ENG/TZ0/XX State and explain whether or not the combustion of hex-1-ene is spontaneous at 25oC. ...................................................................... ...................................................................... [1] (e) Calculate the enthalpy change, H 4 for the reaction C + 2H 2 + 1 O 2 CH 3OH 2 using Hess's Law, and the following information. CH 3OH + 1 1 O 2 CO 2 + 2H 2 O 2 C + O 2 CO 2 H 2 + 1 O2 H 2O 2 H1 = -676 kJ mol-1 H 2 = -394 kJ mol-1 H 3 = -242 kJ mol-1 H 4 [4] ...................................................................... ...................................................................... ...................................................................... ...................................................................... ...................................................................... ...................................................................... ...................................................................... ...................................................................... 2206-6102 Turn over 0312 4 2. (a) M06/4/CHEMI/HP2/ENG/TZ0/XX [3] Use the data below to calculate the relative molecular mass of thallium bromide, TlBr3, to two decimal places. Isotope 203 205 79 81 Tl Tl Percentage Abundance 29.52 70.48 50.69 49.31 Br Br ...................................................................... ...................................................................... ...................................................................... ...................................................................... (b) The value of the relative molecular mass of hydrogen bromide is 80.91, correct to two decimal places. Explain why no molecule in a sample of hydrogen bromide has this M r value. ...................................................................... ...................................................................... ...................................................................... ...................................................................... (c) State the full electron configuration for a bromide ion. ...................................................................... (d) Write the symbol for the ion with a 2 + charge which has the electron configuration of 1s 2 2s 2 2p 6 . ...................................................................... (e) Write the symbols for three other species, which also have the electron configuration of 1s 2 2s 2 2p 6 . ...................................................................... ...................................................................... ...................................................................... ...................................................................... [2] [1] [1] [2] 2206-6102 0412 5 3. M06/4/CHEMI/HP2/ENG/TZ0/XX The reaction below represents the reduction of iron ore to produce iron. 2Fe 2 O3 + 3C 4Fe + 3CO 2 A mixture of 30 kg of Fe 2 O3 and 5.0 kg of C was heated until no further reaction occurred. Calculate the maximum mass of iron that can be obtained from these masses of reactants. .......................................................................... .......................................................................... .......................................................................... .......................................................................... .......................................................................... .......................................................................... .......................................................................... .......................................................................... .......................................................................... .......................................................................... [5] 2206-6102 Turn over 0512 6 4. (a) (i) Define oxidizing agent in terms of electron transfer. M06/4/CHEMI/HP2/ENG/TZ0/XX [1] ................................................................. ................................................................. (ii) Deduce the change in oxidation number of chromium in the reaction below. State with a reason whether the chromium has been oxidized or reduced. Cr2 O7 2- + 14H + + 6Fe 2+ 2Cr 3+ + 6Fe3+ + 7H 2 O ................................................................. ................................................................. ................................................................. ................................................................. (b) Iron in food, in the form of Fe3+ , reacts with ascorbic acid (vitamin C), C6 H8O6, to form dehydroascorbic acid, C6 H 6 O6. (i) Write an ionic half-equation to show the conversion of ascorbic acid to dehydroascorbic acid in aqueous solution. ................................................................. ................................................................. (ii) In the other ionic half-equation Fe3+ is converted to Fe 2+ . Deduce the overall equation for the reaction between C6 H8O6 and Fe3+ . ................................................................. ................................................................. [1] [1] [2] 2206-6102 0612 7 5. (a) State two characteristics of a homologous series. M06/4/CHEMI/HP2/ENG/TZ0/XX [2] ...................................................................... ...................................................................... ...................................................................... ...................................................................... (b) Describe a chemical test to distinguish between alkanes and alkenes, giving the result in each case. ...................................................................... ...................................................................... ...................................................................... ...................................................................... ...................................................................... ...................................................................... (c) Some alcohols are oxidized by heating with acidified potassium dichromate(VI). If oxidation does occur, identify the possible oxidation products formed by each of the alcohols below. Indicate if no oxidation occurs. Butan1ol ...................................................................... ...................................................................... Butan2ol ...................................................................... ...................................................................... 2methylpropan2ol ...................................................................... ...................................................................... [3] [4] 2206-6102 Turn over 0712 8 SECTION B M06/4/CHEMI/HP2/ENG/TZ0/XX Answer two questions. Write your answers on the answer sheets provided. Write your session number on each answer sheet, and attach them to this examination paper and your cover sheet using the tag provided. 6. Consider the following reaction in the Contact process for the production of sulfuric acid for parts (a) to (f) in this question. 2SO 2 + O 2 2SO3 (a) (b) Write the equilibrium constant expression for the reaction. (i) (ii) (c) (d) State the catalyst used in this reaction of the Contact process. State and explain the effect of the catalyst on the value of the equilibrium constant and on the rate of the reaction. [1] [1] [4] [2] Use the collision theory to explain why increasing the temperature increases the rate of the reaction between sulfur dioxide and oxygen. Using Le Chatelier's principle explain the effect on the position of equilibrium of (i) (ii) increasing the pressure at constant temperature. removing sulfur trioxide. [2] [2] (e) Using the following data, explain whether the above reaction is exothermic or endothermic. Temperature / K 298 500 700 Equilibrium constant K c / dm 3 mol -1 9.77 1025 8.61 1011 1.75 106 [2] (f) 1.50 mol of SO 2 and 2.00 mol of O 2 are placed in a 1.50 dm3 flask and heated at 400 oC until equilibrium is reached. The final equilibrium mixture contained 0.500 mol of SO3. Calculate the equilibrium constant, K c of the reaction at this temperature, include units in your answer. [5] (This question continues on the following page) 2206-6102 0812 9 (Question 6 continued) (g) (i) M06/4/CHEMI/HP2/ENG/TZ0/XX Using the data below, state and explain the relationship between enthalpy of vaporization and intermolecular forces. Substance Standard enthalpy of vaporization H v0 / kJ mol-1 Pentane 27 Propanoic acid 57 [3] (ii) Draw a graph to show how the vapour pressure of pentane changes as it is heated from its melting point to its boiling point. Explain this change in terms of the kinetic theory. [3] 2206-6102 Turn over 0912 10 7. (a) (b) M06/4/CHEMI/HP2/ENG/TZ0/XX [3] Draw the Lewis structures for the compounds XeF4, PF5 .and BF4 - . Use the valance shell electron pair repulsion (VSEPR) theory to predict the shapes of the three compounds in (a). State and explain the bond angles in each of the three compounds. State the meaning of the term hybridization. State the type of hybridization shown by the nitrogen atoms in N 2, N 2 H 2 and N 2 H 4 . By referring to the N 2 H 2 molecule describe how sigma () and pi () bonds form and describe how single and double bonds differ. (i) (ii) Explain why the first ionization energy of magnesium is lower than that of fluorine. Write an equation to represent the third ionization energy of magnesium. Explain why the third ionization energy of magnesium is higher than that of fluorine. Explain why sodium has a lower melting point than magnesium. By referring to their structure and bonding explain why magnesium oxide has a higher melting point than sulfur dioxide. [3] [4] [4] [2] [3] [3] [3] (c) (d) (e) (f) (i) (ii) 2206-6102 1012 11 8. (a) (i) (ii) Define the term pH. M06/4/CHEMI/HP2/ENG/TZ0/XX [1] A 25.0 cm3 sample of 0.100 mol dm -3 hydrochloric acid was placed in a conical flask, and 0.100 mol dm -3 sodium hydroxide is added until a total of 50.0 cm3 had been added. Sketch a graph of pH against volume of NaOH(aq) added, clearly showing the volume of NaOH(aq) needed for complete reaction and the pH values at the start, the equivalence point and finish. [4] (iii) The experiment in (a) (ii) was repeated, but with a 25.0 cm3 sample of 0.100 mol dm -3 ethanoic acid in the conical flask instead of the hydrochloric acid. Use information from Table 16 of the Data Booklet to calculate the pH at the start of the experiment. State the approximate pH value at the equivalence point. (b) (i) (ii) (c) (i) (ii) (d) Describe how an indicator, HIn, works. Name a suitable indicator for the reaction between ethanoic acid and sodium hydroxide. Use information from Table 17 in the data booklet to explain your choice. Identify two substances that can be added to water to form a basic buffer solution. Describe what happens when a small amount of acid solution is added to the buffer solution prepared in (i). Use an equation to support your explanation. [5] [3] [2] [1] [2] [5] [2] Define the terms Brnsted-Lowry acid and Lewis acid. For each type of acid, identify one example other than water and write an equation to illustrate the definition. Predict and explain whether an aqueous solution of 0.10 mol dm -3 AlCl3 will be acidic, alkaline or neutral. (e) 2206-6102 Turn over 1112 12 9. (a) M06/4/CHEMI/HP2/ENG/TZ0/XX Given the structures of the repeating units of the polymers below, identify the monomers from which they are formed. (i) (ii) (iii) [1] [1] [2] (b) Describe the essential difference between the structures of monomers that form addition polymers and the structures of monomers that form condensation polymers. Draw and name an isomer of ethanoic acid, CH 3COOH. (i) (ii) State the name of the reagent and the conditions required to convert ethanoic acid to methyl ethanoate. Write an equation for the reaction. Discuss two physical properties that differ for ethanoic acid and methyl ethanoate. [2] [2] [3] [2] (c) (d) (iii) Deduce the ratios of the areas under the peaks in the 1 H NMR spectrum of ethanoic acid and methyl ethanoate. (e) (i) There are four structural isomers with the formula C4 H 9 Cl , one of which is optically active, CH 3CHClCH 2 CH 3. State the name of this isomer and explain why it is optically active. Outline how the two optical isomers can be distinguished experimentally. [2] [2] [2] [2] (ii) (iii) Draw the structure of the three other structural isomers of C4 H 9 Cl. (iv) Identify one isomer in (iii) that undergoes a substitution reaction mainly by a SN 2 mechanism. (v) Write the SN 2 mechanism for the reaction that occurs when the isomer identified in (iv) is warmed with aqueous sodium hydroxide. Use curly arrows to present the movement of electron pairs. [1] [3] 2206-6102 1212 ...
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This note was uploaded on 05/02/2008 for the course CHEM 142,152,16 taught by Professor Unknown during the Spring '08 term at University of Washington.

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