AJC H1 CHEM P2 QP

AJC JC2 PRE NAME:__ CHEMIS Higher 1 Paper 2 Candidates Additional M READ TH Write your Write in dar You may us Do not use Section A Answer all Section B Answer tw o Start each At the end The numbe Paper (33% / ELIM 2015 _________ STRY s answer Se Materials: ESE INST name, PDG rk blue or b se a pencil staples, pa the questio o questions question on of the exam er of marks r 1 %) Q /30 AND 2015 JC _________ ection A on Data Bo Writing TRUCTION G and regist lack pen. for any diag aper clips, h ons. s on separa n a fresh sh mination, fas is given in b S Q1 Q This DERSON C 2 PREL _________ the Questio ooklet paper NS FIRST ter number grams, grap highlighters, te writing pa eet of pape sten all your brackets [ ] For Section A Q2 Q 3 document c 8872/02/H1 N JUNIO LIMINARY _____ on Paper. on all the w phs or roug , glue or cor aper. er. r work secu ] at the end Examiner’ Pap 3 Q4 Fina G consists of 1 OR COL Y EXAMI work you ha h working. rrection fluid urely togethe of each qu s Use per 2 (67% Sec al marks Grade 14 printed p LEGE NATION nd in. d. er. estion or pa %) ction B pages. S PDG 16 Septe art question T / 1 [Turn ov :_____ /14 8872/02 ember 2015 2 hours n. Total / 80 100 ver 4 2 5 s

AJC JC2 PRELIM 2015 8872/02/H1 2 Section A Answer all the questions in this section in the spaces provided. 1 (a) Na, Si and P are elements found in the third period of the Periodic Table. The ionic radii of Na, Si and P are listed in the Data Booklet. State and explain the differences between the (i) ionic radii of Na and Si …………………………………………………………………………………………………… …………………………………………………………………………………………………… (ii) ionic radii of Si and P …………………………………………………………………………………………………… …………………………………………………………………………………………………… [3] (b) A, B, C and D are oxides of the third period elements. Some properties of the oxides are given in the table. oxide melting point / oC electrical conductivity when molten reaction with H2O resulting pH A 2850 good very little 8 B 1720 poor none 7 C 1280 good exothermic 14 D 580 poor exothermic 1 (i) The structures of A, B, C and D can be simple or giant, and their bonding can be covalent or ionic. Use these terms to describe the structure and bonding in each of the oxides A, B, C and D. Structure Bonding A …….……………………… …….……………………… B …….……………………… …….……………………… C …….……………………… …….……………………… D …….……………………… …….………………………

3 AJC JC2 PRELIM 2015 8872/02/H1 [Turn over (ii) Hence, suggest possible identities of A, B, C and D. Identity A …….……………………… B …….……………………… C …….……………………… D …….……………………… [4] (c) The melting points of sodium chlori de and silicon tetrachloride are 801 oC and –70 oC respectively. Explain the difference in the melting points in terms of the structure of, and bonding in, the two chlorides. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. [2] [Total: 9]

AJC JC2 PRELIM 2015 8872/02/H1 4 2 (a) Kerosene is a combustible hydrocarbon liquid widely used as a fuel in industry and households. It is commonly used to power jet engines of aircraft and also used as a cooking and lighting fuel in homes. The formula of kerosene may be taken as C14H30. (i) Using the molecular formula of kerosene, write a balanced equation for its complete combustion in air, including state symbols. …………………………………………………………………………………………………… (ii) Use the relevant bond energies from the Data Booklet to calculate a value for the enthalpy change of combustion of kerosene. (iii) The enthalpy change of combustion of diesel fuel is about –45 kJ g –1. Based on your calculations, suggest which of the fuel, kerosene or diesel fuel, is a more efficient fuel. Give a reason for your answer. …………………………………………………………………………………………………… …………………………………………………………………………………………………… [6]

5 AJC JC2 PRELIM 2015 8872/02/H1 [Turn over (b) Another source of fuel comes from fossil fuels. They are found in deposits beneath the ground and have been formed from plants and anima ls that lived up to 300 million years ago. Most of the sulfur present in fossil fuels is removed at oil refineries. It is used to produce SO 2 which is converted, in the Contact process, into SO 3 which is used for the manufacture of sulfuric acid. The diagram below shows an energy cycle involving SO 2. (i) In the energy cycle above, what enthalpy change is represented by H 1? …………………………………………………………………………………………………… (ii) At 298 K, Hc o(SO2) = –99 kJ mol–1 and Hf o(SO2) = –297 kJ mol–1. Use these data to calculate the standard enthalpy change of formation of SO3. [3] [Total: 9] 2SO2(g) + O2(g) 2SO3(g) 2S(s) + 3O2(g) H1 H2 H3 energy

AJC JC2 PRELIM 2015 8872/02/H1 6 3 (a) Esters can be prepared in the laboratory by heating carboxylic acid and alcohol with excess concentrated sulfuric acid. The diagram below shows a reflux set–up that is used to prepare a sample of the ester with the molecular formula of C 5H10O2. water out water in reflux condenser clamp heating mantle ethanoic acid and alcohol E + conc. H2SO4 round-bottom flask Alcohol E gives a yellow precipitate with alkaline aqueous iodine. (i) Suggest the structural formula of alcohol E. (ii) Hence, suggest the structure of the ester formed in this reaction. (iii) Write a balanced equation for the hydrolysis of the ester you have suggested in (a)(ii) in basic conditions. …………………………………………………… …………………………………………….... (iv) What is a possible organic impurity present in the reaction mixture? …………………………………………………… ……………………………………………....

7 AJC JC2 PRELIM 2015 8872/02/H1 [Turn over (v) Describe one chemical test to confirm the identity of the impurity. You should state the reagents and conditions you would use and what observation you would make. …………………………………………………… …………………………………………….... …………………………………………………… …………………………………………….... …………………………………………………… …………………………………………….... [6] (b) Benzylamine can be made from methylbenzene in two steps. CH3 CH2NH2 2 steps State reagents and conditions for each of the two steps in the following synthesis, and give the structure of the intermediate compound. Step I Reagent: ……………………………………………………………… Condition: …………………………………………………………….. Step II Reagent: ……………………………………………………………… Condition: …………………………………………………………….. structure of intermediate [3] [Total: 9]

AJC JC2 PRELIM 2015 8872/02/H1 8 4 Acetals are compounds formed when aldehydes are reacted with an alcohol in the presence of an acid catalyst. H + CH3CH2CHO(l) + 2CH3CH2OH(l) CH3CH2CH(OCH2CH3)2(l) + H2O(l) propanal ethanol acetal F A student mixed 0.10 mol of propanal in a conical flask with 9.2 g of ethanol in 25.0 cm 3 of an inert solvent dioxan. Then, he carefully added concentrated sulfuric acid, H 2SO4. The flask was sealed with a stopper and allowed to equilibrate in a thermostatic water bath. After equilibrium is reached, the student titrated quickly the entire contents of the conical flask with a solution containing aqueous NaOH and 1.00 mol dm ‒3 aqueous KMnO4, from a burette. The solution turned permanently purple when 25.30 cm 3 of KMnO4 had been added. The student postulated that the following equa