2016 C1 Promotional Exam Paper 2

This document consists of 11 printed pages. HWA CHONG INSTITUTION C1 Promotional Examination Higher 2 NAME CT GROUP 16S CHEMISTRY Paper 2 Structured questions Candidates answer on the Question Paper. Additional Materials: Data Booklet. 9729/02 30 September 2016 1 hour 10 minutes READ THESE INSTRUCTIONS FIRST Write your name and CT group on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. 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. A Data Booklet is provided. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. FOR EXAMINERS’ USE ONLY Paper 1 Paper 2 Paper 3 Percentage Multiple Choice Structured Free Response 100 Q1 / 12 Q1 / 15 Q2 / 13 Q2 / 15 Q3 / 15 Q3 / 4 / 20 Deductions Deductions / 20 Subtotal: / 40 Subtotal: / 50

2 2016 HCI C1 H2 Chemistry Promotional Exam / Paper 2 Answer all the questions in this section. 1 Fatty acids are carboxylic acids with a long hydrocarbon chain. The hydrocarbon chain can either be saturated or unsaturated. (a) Caprylic acid is an example of a saturated fatty acid. When caprylic acid dissolves in a solvent, the hydrocarbon chain and the carboxylic acid functional group interact differently with the solvent. Caprylic acid has minimal solubility in water, but is soluble in tetrachloromethane, CCl4. (i) State the intermolecular forces of attraction acting between water molecules and between CCl4 molecules. Water: …………………………………… CCl4: …………….………………………… [1] (ii) In the table below, state the interaction that will occur between the relevant part of caprylic acid and water and CCl4 respectively. Interaction with: Water CCl4 Hydrocarbon chain of caprylic acid Carboxylic acid functional group of caprylic acid [2] (iii) Using your answers in (a)(i) and (a)(ii), explain why caprylic acid has minimal solubility in water, but is soluble in CCl4. …………………………………………………….……………………………………............ …………………………………………………….……………………………………............ …………………………………………………….……………………………………............ [1]

3 2016 HCI C1 H2 Chemistry Promotional Exam / Paper 2 (b) In order to determine the degree of unsaturation of the hydrocarbon chains in fatty acids, the fatty acid is dissolved in CCl4. A known excess of Br2 or ICl is added in the dark, and further analysis is done to determine how much Br2 or ICl reacted with the fatty acid. (i) Br2 and ICl react with the fatty acids in an electrophilic addition re