IJC H2 CHEM P3

INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION 2 in preparation for General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY Paper 3 Free Response Candidates answer on separate paper. Additional Materials: Writing Papers Data booklet 9746/03 17 September 2009 2 hours 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 4 out of 5 questions. You are advised to show all working in calculations. You are reminded of the need for good English and clear presentation in your answers. You are reminded of the need for good handwriting. Your final answers should be in 3 significant figures. At the end of the examination, fasten all your work securely together. The number of marks is given in the brackets [ ] at the end of each question or part question. This document consists of 11 printed pages and 1 blank page. Innova Junior College [Turn over

PRELIM 2  INNOVA 9746/03/09 [Turn over 2 Answer 4 out of 5 questions 1 (a) Compound A reacts with bromine to form compound B as follows. Describe the mechanism for this reaction, including curly arrows showing the movement of electrons, and all charges. [3] (b) The following table gives the boiling points and relative molecular masses for four organic compounds. Compound Formula Mr b.p. / °C C NH2CH2CH2COOH 89 235 D HOCH2CH2COOH 90 75 E CH3CH2CH2CH2CH3 72 36 F (CH3)4C 72 10 By comparing C with D and E with F , suggest explanations for the similarities or differences in the boiling points within each of these two pairs. [4] (c) (i) When barium peroxide, BaO 2 is added to water, barium hydroxide and compound G are formed. When the solution is acidified, and added to potassium manganate solution, a colourless solution is formed. Identify compound G. Write down the equation of barium peroxide with water and explain the observation. (ii) Explain whether barium nitrate or calcium nitrate will be more thermally stable under strong heat. [4] (d) The standard reduction potential for the following reaction is +0.20 V. 2HCO 2 – (aq) + 2CO2 (g) + 6H+ (aq) + 6e  C4H4O6 2– (aq) + 2H2O (l) Using relevant information in the Data Booklet, calculate the E θ cell for the reaction when hydrogen peroxide solution is added to an acid solution containing CO 2, HCO2 – and C4H4O6 2– ions. Hence, predict whether the reaction is feasible and construct balanced equations for any reactions that occur. [2]

3 (e) When zinc metal is added to green solution of aqueous V3+ under acidic medium, the solution turns violet. The excess zinc is filtered off and the violet solution is allowed to stand for several hours. The solution slowly turns green. Using relevant information in the Data Booklet , explain the above reactions and construct balanced equations for any reactions that occur. [3] (f) An alkane H with the formula C 6H14 reacts with chlorine to yield three compounds with the formula C6H13Cl: J, K and L. Of these only K and L can react with ethanolic potassium hydroxide. Moreover, K and L yield the same product. Deduce the structure of H, J, K and L. [4] [Total:20] PRELIM 2  INNOVA 9746/03/09 [Turn over

4 2 (a) The table shows data, at 298K, for the following reaction. H2(g) + I2 (s) 2H I (g) ΔS / J mol-1 K-1 H2(g) 130.6 I2 (s) 116.8 HI (g) 206.5 (i) Calculate the entropy change of the reaction. (ii) Given that enthalpy change of formation of H I is +26.5 kJ mol -1, calculate ΔG of the reaction. [3] (b) The enthalpy change of evaporation of I2 at its boiling point of 183 oC is + 41.8 kJ mol-1. (i) Calculate the entropy change of evaporation of iodine. (ii) Explain the significance of the sign of entropy change found in part (i). [2] (c) When boron trichloride (BCl3) and iodine monochloride (ICl) react, a single product is formed. This product, compound M, contains an anion and one cation. The cation acts as an electrophile in the formation of iodobenzene from benzene. (i) Suggest a formula for compound M. (ii) Predict the shape and bond angle of the anion in compound M. (iii) Compound N undergoes the following reaction: 1. Suggest a structural formula of N. 2. Suggest reagents and conditions necessary for reaction Q. 3. Describe simple chemical test which could be used to distinguish compound P from 2,3-dichlorobutane. You should include the reagent, the reaction conditions, and the positive observation. 4. Suggest a structural formula of the product when phenol is shaken with ICl in trichloroethane. PRELIM 2  INNOVA 9746/03/09 [Turn over

5 (iv) Compare and explain the difference in the relative rates of hydrolysis of compound R and S. State the reagents and conditions for the relevant hydrolysis reactions. [9] (d) Consider the following reaction scheme undergone by sodium thiosulphate with halogens T and U. (i) Suggest a suitable identity each for T and U. (ii) Write a balanced ionic equation for the reaction between Na2S2O3 and U. (iii) Use relevant data from the Data Booklet to explain the different reactions of halogen T and U with sodium thiosulphate. (iv) Suggest a simple test which can be used to distinguish between T and U. You should state how each compound behaves in the test. [6] [Total:20] PRELIM 2  INNOVA 9746/03/09 [Turn over

6 3 (a) When an organic compound Procaine, V, C 13H20N2O2, is boiled with aqueous sodium hydroxide, it gives two compounds, one of which has the following structure W shown below and another compound X. Compound W When aqueous bromine is added to compound X, the orange brown solution decolourised, white precipitate, Y, C 7H4NO2Br2 –, is formed and steamy fumes is liberated. (i) Deduce the structures for V, X and Y. Give an account of the chemistry involved. (ii) Describe one simple chemical test you could carry out to distinguish compound W from Z. State the reagents, conditions and observations expected. Compound Z [7] (b) (i) Explain why transition metals form complexes readily. (ii) When aqueous ammonia is gradually added to a solution containing copper (II) ions, a blue precipitate is formed. To separate samples of the blue precipitate:  The precipitate