IB SL Chem 2 Sem 1 Exam 2013
advertisement
IB Chemistry 2 SL Semester 1 Exam 2013 Version 3 1. 2. 3. How do the bond angles in CH4, NH3 and H2O compare? A. CH4 = NH3 = H2O B. CH4 < NH3 < H2O C. NH3 < CH4 < H2O D. H2O < NH3 < CH4 Name:_____________________ IB Chemistry 2 SL Sem. 1 Exam 2013 4. 5. 6. IB Chemistry 2 SL Sem. 1 Exam 2013 7. Which species behave as Brønsted-Lowry acids in the following reversible reaction? H2PO4–(aq) + CN–(aq) 8. A. HCN and CN– B. HCN and HPO42– C. H2PO4– and HPO42– D. HCN and H2PO4– HCN(aq) + HPO42–(aq) For equal volumes of 1.0 mol dm–3 solutions of hydrochloric acid, HCl(aq), and methanoic acid, HCOOH(aq), which statements are correct? 9. 10. I. HCl dissociates more than HCOOH II. HCl is a better electrical conductor than HCOOH III. HCl will neutralize more NaOH than HCOOH A. I and II only B. I and III only C. II and III only D. I, II and III Which property is characteristic of acids in aqueous solution? A. Acids react with ammonia solution to produce hydrogen gas and a salt. B. Acids react with metal oxides to produce oxygen gas, a salt and water. C. Acids react with reactive metals to produce hydrogen gas and a salt. D. Acids react with metal carbonates to produce hydrogen gas, a salt and water. A solution of acid A has a pH of 1 and a solution of acid B has a pH of 2. Which statement must be correct? A. Acid A is stronger than acid B B. [A] > [B] C. The concentration of H+ ions in A is higher than in B D. The concentration of H+ ions in B is twice the concentration of H+ ions in A IB Chemistry 2 SL Sem. 1 Exam 2013 11. 12. What happens to iodine when iodate ions, IO3–, are converted to iodine molecules, I2? A. It undergoes reduction and its oxidation number changes from –1 to 0 B. It undergoes oxidation and its oxidation number changes from –1 to 0 C. It undergoes reduction and its oxidation number changes from +5 to 0 D. It undergoes oxidation and its oxidation number changes from +5 to 0 Consider the following reactions of three unknown metals X, Y and Z. 2XNO3(aq) + Y(s) → 2X(s) + Y(NO3)2(aq) Y(NO3)2(aq) + Z(s) → No reaction 2XNO3(aq) + Z(s) → 2X(s) + Z(NO3)2(aq) What is the order of increasing reactivity of the metals (least reactive first)? 13. 14. A. X<Y<Z B. X<Z<Y C. Z<Y<X D. Y<Z<X Which statement about the electrolysis of molten sodium chloride is correct? A. A yellow-green gas would be produced at the negative electrode. B. A silvery metal is produced at the positive electrode. C. Chloride ions are attracted to the positive electrode and undergo oxidation. D. Sodium ions are attracted to the negative electrode and undergo oxidation. Which experimental procedure is most likely to lead to a large systematic error? A. Determining the concentration of an alkali by titration with a burette B. Measuring the volume of a solution using a volumetric pipette C. Determining the enthalpy change of neutralization in a beaker D. Measuring the volume of a gas produced with a gas syringe IB Chemistry 2 SL Sem. 1 Exam 2013 15. Zinc is higher in the reactivity series than iron. In the cell shown, in which direction do the electrons flow in wire X and which metal is oxidized? Zn Fe FeSO4 (aq) ZnSO4 (aq) Electron flow Oxidized A. Fe to Zn Fe B. Zn to Fe Fe C. Fe to Zn Zn D. Zn to Fe Zn (Total 1 mark) 16. In the electrolytic cell shown, at which electrode would you place an object to be plated with silver, and what is the process taking place at that electrode? AgCl2 (l) Electrode Process A. P reduction B. Q reduction C. P oxidation D. Q oxidation IB Chemistry 2 SL Sem. 1 Exam 2013 17. Halogenoalkanes can undergo SN1 and SN2 reactions with aqueous sodium hydroxide. Which halogenoalkane will react fastest with a 0.1 mol dm–3 solution of aqueous sodium hydroxide? 18. A. 2-chloro-2-methylpropane B. 2-iodo-2-methylpropane C. 1-chlorobutane D. 1-iodobutane Which is the correct classification of these alcohols? 1 2 1 19. 2 3 3 A. tertiary secondary primary B. tertiary primary secondary C. tertiary tertiary secondary D. secondary primary secondary What is the product of the following reaction? 2 Cr2 O 7 /H CH3CH(OH)CH3 A. CH3COOH B. CH3COCH3 C. CH3CH2COOH D. CH3CH2CH3 IB Chemistry 2 SL Sem. 1 Exam 2013 20. 21. 22. Which of the following substances are structural isomers of each other? I. CH3(CH2)3CH3 II. (CH3)2CHCH3 III. CH3CH(CH3)CH2CH3 A. I and II only B. I and III only C. II and III only D. I, II and III Which monomer could be used to form a polymer with the following repeating unit? A. CH3CH2Cl B. CH2ClCH2Cl C. CH2CHCl D. CHClCHCl Which reaction pathway describes how ethanol can be formed? A. addition elimination chloroethane ethanol ethene B. substitution nucleophilic substitution chloroethane ethanol ethane C. substitution ethanol ethene D. addition ethanol ethane IB Chemistry 2 SL Sem. 1 Exam 2013 23. Which three compounds can be considered to be a homologous series? A. CH3OH, CH3CH2OH, CH3CH2CH2OH B. CH3CH2OH, C. CH3CH2CH(OH)CH3, CH3CH2CH2CH2OH, D. CH3CH2CH2CH2OH, CH3CH2OCH2CH3, CH3CHO, CH3COOH (CH3)3COH (CH3)2CH2CHO End of Paper 1. Raise your hand for this to be collected and you may start paper 2. IB Chemistry 2 SL Sem. 1 Exam 2013 Paper 2: Please write all responses in the space provided. 1. (i) Name:_____________________ Define a Brønsted-Lowry acid. ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ (1) (ii) Deduce the two acids and their conjugate bases in the following reaction: H2O(l) + NH3(aq) OH–(aq) + NH4+(aq) ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ (2) (iii) Explain why the following reaction can also be described as an acid-base reaction. F–(g) + BF3(g) BF4–(s) ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ (2) (Total 5 marks) IB Chemistry 2 SL Sem. 1 Exam 2013 2. The equations of two acid-base reactions are given below. Reaction A NH3(aq) + H2O(l) NH 4 (aq) + OH–(aq) The reaction mixture in A consists mainly of reactants because the equilibrium lies to the left. Reaction B NH2–(aq) + H2O(l) NH 3 (aq) + OH–(aq) The reaction mixture in B consists mainly of products because the equilibrium lies to the right. (i) For each of the reactions A and B, deduce whether water is acting as an acid or a base and explain your answer. ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................(2) (ii) In reaction B, identify the stronger base, NH2– or OH– and explain your answer. ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................(2) (iii) In reactions A and B, identify the stronger acid, NH4+ or NH3 (underlined) and explain your answer. ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................(2) (Total 6 marks) IB Chemistry 2 SL Sem. 1 Exam 2013 3. Describe two different methods, one chemical and one physical, other than measuring the pH, that could be used to distinguish between ethanoic acid and hydrochloric acid solutions of the same concentration. ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ (Total 4 marks) 4. An acidified solution of potassium dichromate is often used as an oxidizing agent in organic chemistry. During the oxidation reaction of ethanol to ethanal the dichromate ion is reduced to chromium(III) ions according to the following unbalanced half-equation. Cr2O72–(aq) + H+(aq) + e– → Cr3+(aq) + H2O(l) (i) Describe the colour change that will be observed in the reaction. ...................................................................................................................................... (1) (ii) Deduce the oxidation number of chromium in Cr2O72–. ...................................................................................................................................... (1) (iii) State the balanced half-equation for the reduction of dichromate ions to chromium(III) ions. ...................................................................................................................................... ...................................................................................................................................... (1) IB Chemistry 2 SL Sem. 1 Exam 2013 (iv) Deduce the half-equation for the oxidation of ethanol to ethanal and hence the overall redox equation for the oxidation of ethanol to ethanal by acidified dichromate ions. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... .............................................................................................................................................. (3) (v) Explain why it is necessary to carry out the reaction under acidic conditions. ............................................................................................................................................... ............................................................................................................................................... (1) (vi) Identify the organic product formed if excess potassium dichromate is used and the reaction is carried out under reflux. ............................................................................................................................................... ............................................................................................................................................... (1) (Total 8 marks) 5. The word redox comes from a combination of the terms reduction and oxidation. Redox reactions affect our daily lives. The overall reaction that takes place in a voltaic cell is shown below. Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l) (i) Determine the oxidation number of lead in Pb, PbO2 and PbSO4. ..................................................................................................................................... (1) IB Chemistry 2 SL Sem. 1 Exam 2013 (ii) Deduce the oxidation and reduction half-equations taking place at the negative lead electrode (anode) and the positive lead(IV) oxide electrode (cathode). Deduce the oxidizing and reducing agents and state the direction of the electron flow between the electrodes. ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ (4) (iii) In order to determine the position of three metals in a reactivity series, the metals were placed in different solutions of metal ions. The table below summarizes whether or not a reaction occurred. Ag+(aq) Ag(s) Cu(s) Reaction Pb(s) Reaction Cu2+(aq) Pb2+(aq) No reaction No reaction No reaction Reaction State the equations for the three reactions that take place. Use this information to place the metals Ag, Cu and Pb in a reactivity series, with the strongest reducing agent first, and explain your reasoning. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... (Total 10 marks) (5) IB Chemistry 2 SL Sem. 1 Exam 2013 6. Below is a schematic diagram representing some reactions of ethene. The letters A–D represent the organic compounds formed from the reactants and catalysts shown. Deduce the structural formulas of compounds A, B, C, and D and state the IUPAC name of compound C. A: B: C: IUPAC name: .............................................................................................................. D: (Total 5 marks) IB Chemistry 2 SL Sem. 1 Exam 2013 7. Consider the following sequence of reactions. reaction 1 reaction 2 reaction 3 RCH2Br RCH2OH RCOOH RCH3 RCH3 is an unknown alkane in which R represents an alkyl group. (a) The alkane contains 81.7 % by mass of carbon. Determine its empirical formula, showing your working. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... (b) (3) Equal volumes of carbon dioxide and the unknown alkane are found to have the same mass, measured to an accuracy of two significant figures, at the same temperature and pressure. Deduce the molecular formula of the alkane. ............................................................................................................................................... ............................................................................................................................................... (c) (i) (1) State the reagent and conditions needed for reaction 1. ............................................................................................................................................... ............................................................................................................................................... (ii) (2) State the reagent(s) and conditions needed for reaction 3. ............................................................................................................................................... ............................................................................................................................................... (2) IB Chemistry 2 SL Sem. 1 Exam 2013 8. Consider the following reaction taking place at 375 °C in a 1.00 dm3 closed container. Cl2(g) + SO2(g) (i) SO2Cl2(g) ∆HO = –84.5 kJ Deduce the equilibrium constant expression, Kc, for the reaction. ............................................................................................................................................... (ii) (1) If the temperature of the reaction is changed to 400 °C, predict, stating a reason in each case, whether the equilibrium concentration of SO2Cl2 and the value of Kc will increase or decrease. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... (3) (iii) If the volume of the container is changed to 2.50 dm3, predict, stating a reason in each case, how this will affect the equilibrium concentration of SO2Cl2 and the value of Kc. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... (iv) (3) Suggest, stating a reason, how the addition of a catalyst at constant pressure and temperature will affect the equilibrium concentration of SO2Cl2. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... (2) (Total 9 marks)
