JJC_H2_CHEM_P3

JURONG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS CHEMISTRY 9746/03 Paper 3 Free Response 21 August 2009 2 hours Candidates answer Section A on the Question Paper Additional Materials: Answer Paper Data Booklet Graph Paper READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer any four questions. Begin your answer to each new question on a fresh sheet of writing paper. At the end of the examination, arrange the answers in numerical order and attach the cover sheet on top. A Data Booklet is provided. Do not write anything on the Data Booklet. 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. At the end of the examination, fasten all your work securely together. For Examiner’s Use Section A 1 2 3 4 Section B Answer all questions on separate answer paper. 5 This document consists of 10 printed pages and 2 blank pages. [Turn over

Answer any four questions. 1. Phenol is a powerful disinfectant and has antiseptic properties. Hence it is found in medicinal products such as ear and nose drops, throat lozenges and mouthwashes. (a) The standard enthalpy change of combustion of solid phenol is –3054 kJ mol -1. (i) What is meant by the term standard enthalpy change of combustion? (ii) Write the equation, with state symbols, which represents the standard enthalpy change of combustion of phenol. (iii) Using the following standard enthalpy changes of formation together with data given above, calculate the standard enthalpy change of formation of phenol. H f (CO2) = –394 kJ mol-1 Hf (H2O) = –286 kJ mol-1 (iv) Given that the standard entropy change for the formation of phenol is –384 J K-1mol-1, calculate the value of the standard free energy change, G, for the formation of phenol. [5] (b) 2,4,6-trichlorophenol is a chlorinated phenol which is a stronger germicide than phenol. 2,4,6-trichlorophenol (i) Predict and explain if 2,4,6-trichlorophenol has a larger or smaller K a value as compared to phenol. (ii) Suggest a suitable chemical test to distinguish between 2,4,6-trichlorophenol and phenol. [4] Cl Cl OH Cl Page 2 of 10

1. (c) 1-naphthol, a derivative of phenol, can be used to synthesize compound Q by the following reaction scheme. P 1-naphthol Compound Q (i) Suggest a suitable structure for the inte