SAJC_H1_CHEM_P2_student

1 Name: Class: ST ANDREW’S JUNIOR COLLEGE JC2 Preliminary Examination Chemistry Higher 1 8872/2 Paper 2 17th September 2015 1400 - 1600 2 hours Additional Materials: Writing paper, Data Booklet, OAS READ THESE INSTRUCTIONS FIRST Write your name and civics group on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A: Answer all the questions in this section in the spaces provided. Section B: Answer two questions from this section on separate answer paper. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiners use only: Section A Question 1 Question 3 Question 2 Question 4 Total for Section A Section B Total for Section B Total This document consists of 17 pages including a blank page. [Turn Over 14 10 9 7 40 20 20 40 80

2 [BLANK]

3 Section A Answer all the questions in this section in the spaces provided. 1 Jet airliners use kerosene as fuel. The formula of kerosene can be taken as C14H30. It can be converted into more useful small molecules by the process of cracking. (a) (i) To which homologous series does kerosene belong? [1] (ii) Write a balanced equation to show the cracking of kerosene into heptane, propene and ethene only. [1] (iii) Suggest a use of ethene during the cracking process. [1] (iv) With the aid of an equation, define standard enthalpy change of combustion of kerosene. [1] [Turn over]

4 1 (b) Fill in the boxes with the appropriate structures and state the reagents and conditions of steps I and II. Step I: Step II: [5]

5 1 (c) The propene obtained from cracking of kerosene is bubbled into acidified potassium manganate(VII) solution to form ethanoic acid. 20 cm 3 of the ethanoic acid produced is titrated with 3.0 mol dm -3 aqueous NaOH using a suitable indicator. The average volume of NaOH used is 12.50 cm3. Another 20 cm 3 of the same ethanoic acid is placed into a plastic cup of negligible heat capacity. A 10.0 cm 3 sample of 3.0 mol dm -3 aqueous NaOH, at the same initial temperature, is added into the plastic cup. The temperature of the mixture rises by 12.5 K. (i) Determine the concentration of ethanoic acid. [1] (ii) If the specific heat capacity per unit volume of the mixture is 4.2 J K -1 cm-3, what is the enthalpy change of neutralization of ethanoic acid? [2] (iii) If HC l replaces ethanoic acid in the above experiment, w ould the temperature rise be higher or lower? Explain your answer. [2] [Total: 14 marks]