ACJC_H2_CHEM_P2 Prelim

Index No. Name Form Class Tutorial Class Subject Tutor ANGLO-CHINESE JUNIOR COLLEGE PRELIMINARY EXAMINATIONS Advanced Level CHEMISTRY 9746/02 Higher 2 Paper 2 Structured 24 August 2009 1 hour 30 minutes Candidates answer on the Question Paper Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, index number, form class, tutori al class and subject tutor’s name 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. Answer all questions. A Data Booklet is provided. 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 including the cover page. For Examiner's Use Question no. Marks 1 2 3 4 TOTAL This document consists of 11 printed pages. 9746/02/Prelim/09 ANGLO-CHINESE JUNIOR COLLEGE © ACJC 2009 Department of Chemistry [Turn over

2 1 Carbonyl fluoride, COF 2 (structure as shown below) exists as a toxic gas which reacts rapidly with water to evolve two different acidic gases. C O FF (a) (i) The reaction of carbonyl fluoride with water is found to proceed via the formation of an intermediate as shown: C OH HO F F State the reaction that has occurred to produce the above intermediate. [1] (ii) The above intermediate is found to dissociate rapidly to give two different acidic gases. One of the gases is carbon dioxide. State the identity of the other gas. [1] (iii) Using the above information, write a balanced equation of the reaction between carbonyl fluoride and water. [1] (b) An unknown amount of carbonyl fluoride was reacted with water (in excess). The two acidic gases released is then reacted with NaOH(aq). 25.00 cm 3 of 0.100 mol dm-3 of NaOH(aq) is required for complete neutralisation. (i) Calculate the number of moles of NaOH that has reacted. [1] © ACJC 2009 9746/02/Prelim/09 [Turn over

3 (ii) Calculate the number of moles of CO2 produced. [3] (iii) Using your answer in b(ii), calculate the volume of carbon dioxide in m 3 produced under the conditions of 30 C and 1 atm (assuming ideal gas behaviour). [1] (iv) Calculate the mass of carbonyl fluoride used. [1] (c) Carbonyl fluoride is found to dissociate to form CO 2 and CF4 as shown below: 2COF2(g) CO 2(g) + CF4(g) (i) Given that the Kc value of the above reaction at 1000 C is 2.00, calculate the number of moles of C