ACJC H2 CHEM P1 Prelim

© ACJC 2014 9647/01/Prelim/14 [Turn over 2 Section A For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Wines often contain a small amount of sulfur dioxide that is added as a preservative. The sulfur dioxide content of a wine is found by the following method: A 50 cm 3 sample of white wine is reacted with 40.0 cm 3 of 0.01 mol dm -3 of excess aqueous iodine. The sulfur dioxide in the wine is oxidized to sulfate, SO 4 2-, in the process. The unreacted iodine requires exactly 23.60 cm 3 of 0.02 mol dm -3 sodium thiosulfate for complete reaction. What is the concentration of sulfur dioxide, in mol dm −3 , in the wine? A 1.64 x 10 −3 * B 3.28 x 10 −3 C 4.72 x 10 −3 D 9.44 x 10 −3 2 A sample of 0.16 g of liquid A is vaporised in a graduated syringe at 100 C and 1 atm. The final volume of the syringe that was recorded is 46 cm3. By assuming that 1 mol of vapour occupies 22.4 dm 3 at standard temperature and pressure, what is the relative molecular mass of A? A B C * D

© ACJC 2014 9647/01/Prelim/14 [Turn over 3 n- 3 Which one of the following sets of compounds consists of a giant ionic structure, a giant covalent structure and a simple covalent structure? A C6H5CO2H, P4O10 and BN B BaO2, ICl3 and SnCl2 * C AlCl3, AlF3 and SiC D SiO2, HCl and BeCl2 4 An ion IF4 n− has a square planar structure as shown below. What is the value of n? *A 1 B 2 C 3 D 4 5 Which of the following is a possible configuration of a stable M 3+ ion in the ground state? A 1s 2 2s 2 2p 3 B 1s 2 2s 2 2p 6 3s 2 3p 1 * C 1s 2 2s 2 2p 6 3s 2 3p 6 3d 2 D 1s 2 2s 2 2p 6 3s 2 3p 6 3d 2 4s 2 I F F F F n−

© ACJC 2014 9647/01/Prelim/14 [Turn over 4 6 S4N4 is a thermochomic solid which changes colour with temperature. S 4N4 has a cage structure as shown in the diagram. SS N N N N S S Given the following data, what is the average bond energy of S-N, in kJ mol-1? ∆Hf° (S4N4) = +460 kJ mol-1 ∆Hat° (sulfur) = +279 kJ mol-1 ∆Hat° (nitrogen) = +497 kJ mol-1 (S-S) bond energy in S4N4 = = +204 kJ mol-1 A 155 * B 280 C 395 D 559 7 Self-heating cans can offer benefits to campers without access to a stove or campfire. These soup cans have double walls with an ionic compound such as CaO in a packet and water between the walls. Upon opening the can, the packet breaks, the CaO reacts with water and warms up the soup. CaO (s) + H 2O (l)  Ca(OH)2 (s) What are the signs of ∆H, ∆S and ∆G for the overall process? ∆H ∆S ∆G *A - - - B - + - C + + - D + + +

© ACJC 2014 9647/01/Prelim/14 [Turn over 5 8 Acetals are derived from aldehydes or ketones, formed by reaction with two equivalents of an alcohol in the presence of an acid catalyst. The reaction below is an example of the formation of an acetal from propanone and methanol. H+ CH3COCH3 (l) + 2CH3OH(l) CH 3C(OCH3)2CH3 (l) + H2O(l) acetal Given that the initial and equilibrium concentrations were as follows, what is the equilibrium constant of the reaction? [CH3COCH3] / mol dm-3 [CH3OH] / mol dm-3 [H+] /mol dm-3 [acetal] /mol dm-3 [H2O] /mol dm-3 At start 0.20 0.30 0.05 0.00 0.00 At equilibrium 0.04 A 0.0207 * B 0.207 C 4.14 D 5.17 9 Hardness in tap water can be determined by titrating a water sample against a reagent which forms complex ions with dissolved metal ions. The indicator for this titration requires the pH to be maintained at about 10. Which of the following, in aqueous solution, could be used to maintain this pH? * A Ammonia and ammonium chloride B Ammonium chloride and hydrochloric acid C Sodium ethanoate and ethanoic acid D Sodium hydroxide and sodium ethanoate

© ACJC 2014 9647/01/Prelim/14 [Turn over 6 10 Strontium fluoride, SrF2, has a Ksp of 1.0 x 10-9 mol3 dm-9. When a 50 cm 3 sample of solution X was added to a 50 cm 3 sample of 5.0 x 10 -4 mol dm -3 strontium fluoride solution, a precipitate of strontium fluoride was seen. Which of these solutions is solution X? A 0.001 mol dm-3 NaF * B 0.002 mol dm-3 BaF2 C 0.001 mol dm-3 SrCl2 D 0.002 mol dm-3 SrCrO4 11 Use of the Data Booklet is relevant to this question. Bronze is an alloy of copper and tin. The alloy is used for making tools, weapons and building materials. The circuit shown below was set up. Which of the following observations can be made at the electrodes? Anode reaction Cathode reaction A Tin dissolves preferentially Copper is precipitated B Tin and copper both dissolve Copper is precipitated * C Tin dissolves preferentially Hydrogen is evolved D Tin and copper both dissolve Hydrogen is evolved Bronze

© ACJC 2014 9647/01/Prelim/14 [Turn over 7 12 Brine (concentrated sodium chloride solution) was electrolysed using inert electrodes in a cell. The mixture is stirred so that the products of the electrolysis are able to react. The cell is kept cold throughout the entire process. Which one of the following pairs of substances is among the final products? A Hydrogen and chlorine * B Hydrogen and sodium chlorate(I) C Hydrogen and sodium chlorate(V) D Sodium hydroxide and chlorine 13 Ampicillin is a synthetic der ivative of penicillin. It is an effective drug against some bacteria inflicted diseases. H C NH2 C O NH N O S CH3 CH3 COOH Ampicillin How many enantiomers does ampicillin have? A 8 B* 16 C 32 D 64

© ACJC 2014 9647/01/Prelim/14 [Turn over 8 14 Chlorine gas is bubbled into 2-methylpropane in the presence of ultraviolet rays. Which of the following is not a possible by-product of the reaction? A B C* D 15 Which of the following reactions form a product which can be further oxidised to form a ketone? * A cold dilute KMnO4, KOH (aq) B cold dilute KMnO4, KOH (aq) C cold H2SO4 followed by boiling in H2O D cold H2SO4 followed by b o i l i n gi nH2O

© ACJC 2014 9647/01/Prelim/14 [Turn over 9 16 Which pair of reactions will occur via organic intermediates of the same charge? M CH3CH2CH3  CH3CHClCH3 N (CH3)3CBr  (CH3)3COH P C6H6  C6H5Cl Q CH3COCH3  CH3C(OH)(CN)CH3 A M and N B N and Q C* N and P D P and Q 17 Which graph shows the relative amount of precipitate formed when compound B treated to the following conditions? Cl ClO Cl Compound B M – AgNO3 (aq) at room temperature N – hot NaOH (aq), followed by HNO3 and AgNO3 (aq) A B C D*

© ACJC 2014 9647/01/Prelim/14 [Turn over 10 18 The Wittig reaction converts aldehydes or ketones into alkenes. In this reaction, the carbonyl compound reacts with a phosphorous ylide which is a neutral, dipolar compound. H3C C H3C O P(Ph)3 H3C C H3C C H CH3 + (Ph)3P O C H3C H Phosphorus ylide How many stereoisomers will form when pentane-2,4-dione is reacted with excess of the same phosphorous ylide given in the reaction above? OO Pentane-2,4-dione A 2 B* 3 C 4 D 5

© ACJC 2014 9647/01/Prelim/14 [Turn over 11 19 Warfarin is used as a pesticide against rodents. The structural formula of warfarin is given below. Which of the following statements is true about warfarin? A It has a total of 4 stereoisomers. * B It reacts with ethanoyl chloride to give out white fumes. C It reacts with phosphorus pentachloride to give out white fumes. D It reacts with hot acidified potassium manganate(VII) to form two carbon containing compounds. 20 Steroids are a class of compounds that contains a characteristic arrangement of four cycloalkane rings. The structures of two steroids, estradiol and progesteron, are shown below. HO OH O O Estradiol