SAJC_H2_CHEM_P3_Ans Prelim

1 Name: Class: ST ANDREW’S JUNIOR COLLEGE JC2 Preliminary Examinations Chemistry Higher 2 9647/03 16 September 2016 Paper 3 2 hours Candidates answer on separate paper. Additional Materials: Writing paper, Data Booklet 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. Answer any four questions. You are reminded of the need for good English and clear presentation in your answers. 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. This document consists of 14 printed pages including this page. [Turn over

2 1 Propenoic acid, also commonly known as acrylic acid, is used in the formation of many polymers. (a) Acrylic acid can be synthesised from 2-chloroethanol in the laboratory by the following route. (i) Suggest the structure for intermediate A. [1] (ii) Suggest reagents and conditions for step 2 and for step 3. [2] Step 2: excess conc. H2SO4, 170OC Step 3: H2SO4 (aq), heat (iii) What type of reaction is occurring in step 2? [1] Elimination (b) Acrylic acid is manufactured industrially from the reaction of propene and oxygen gas. (i) Write a balanced equation for this reaction. [1] CH3CH=CH2 + 3/2O2  CH2=CHCO2H + H2O (ii) Propenal was isolated as an intermediate product in the reaction. Draw the structure of propenal. [1] (c) Polyacrylate is used in environmentally -friendly detergents to remove calcium ions and magnesium ions in water. In the manufacture of polyacrylate, acrylic acid was first converted into acrylic chloride, followed by reaction with an alcohol to form a monomer. Polyacrylate is formed when the monomer undergoes polymerisation.

3 (i) Write a balanced equation for the conversion of acrylic acid into acrylic chloride. [1] (ii) Suggest the type of reaction occurring in the for mation of the monomer from acrylic chloride. [1] Nucleophilic substitution/Condensation (iii) Suggest how polyacrylate can remove magnesium ions from water through complex formation. [1] The lone pair of electrons on O of the ester functional group / ligand can form dative bond/coordinate bonds with empty orbitals of the cation. (d) In the kinetic studies of polymerisation, transition element-containing catalysts were used. A copper(I)-containing catalyst is shown below. Cu(I)-nBuPCA catalyst (i) What is the co-ordination number of copper in the Cu(I)-nBuPCA catalyst? [1] 4 (ii) What is the electronic configuration of copper in Cu(I)-nBuPCA? [1] 1s22s22p63s23p63d10