2019 RVHS Prelim P4 QP

River Valley High School Pg 1 of 24 JC 2 H2 Chemistry 9729 Practical Examination 2019 RIVER VALLEY HIGH SCHOOL JC 2 PRELIM PRACTICAL EXAMINATION H2 CHEMISTRY 9729 26 AUGUST 2019 2 HOURS 30 MINUTES ATION II NAME CLASS 18J ( ) INDEX NO. INSTRUCTIONS TO CANDIDATES DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO. Read these notes carefully. Write your name, class and index number in the spaces at the top of this page. Give details of the practical shift and laboratory where appropriate, in the boxes provided. Write in dark blue or black pen. You may use a 2B pencil for any diagrams or graph. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. Shift Laboratory For Examiner’s Use 3 s.f. Units Total 55 22 printed pages and 2 blank pages

River Valley High School Pg 2 of 24 JC 2 H2 Chemistry 9729 Practical Examination 2019 Answer all the questions in the spaces provided. 1 An experiment to investigate the behaviour of acids and bases in aqueous solution For Examiner’s Use For Examiner’s Use FA 1 is 1.00 mol dm–3 sodium hydrogencarbonate, NaHCO3 FA 2 is sodium hydroxide, NaOH, between 1.5 to 2.5 mol dm–3 FA 3 is 2.00 mol dm–3 sulfuric acid, H2SO4 According to the Arrhenius theory of acids and bases, an acid produces H+(aq) ions and a base produces OH–(aq) ions, in aqueous solution. Using the Arrhenius theory, an acid -base neutralisation reaction involves reacting together these two ions to produce water molecules. The equation for this neutralisation reaction is given below. H+(aq) + OH–(aq) H2O(l) ΔHneutralisation = –57.1 kJ mol–1 The reaction between H +(aq) and OH –(aq) involves bond formation and is exothermic. It is possible to make use of this fact to perform a thermometric titration. This task involves two different acid-base reactions. The first reaction is between sodium hydrogencarbonate, FA 1, and sodium hydroxide, FA 2. Reaction 1: NaHCO3(aq) + NaOH(aq) Na2CO3(aq) + H2O(l) ΔHreaction 1 The molar enthalpy change for Reaction 1, ΔHreaction 1, is the enthalpy change when 1.00 mol of NaHCO3 reacts completely with NaOH. Instead of using an indicator to determine the endpoint, you will perform a thermometric titration to determine the equivalence point of the reaction. The equivalence point is that point where H +(aq) from the acid and OH –(aq) from the base are present in equal molar amounts. The second reaction is between sodium hydrogencarbonate, FA 1, and sulfuric acid, FA 3. Reaction 2: NaHCO3(aq) + ½H2SO4(aq) ½Na2SO4(aq) + H2O(l) + CO2(g) ΔHreaction 2 The molar enthalpy change for React