AJC H2 Chem 2012 Prelim P2 QP

NAME:______________________________ PDG:__________ Register No: _____ ANDERSON JUNIOR COLLEGE Preliminary Examinations 2012 CHEMISTRY 9647/02 Higher 2 13 September 2012 Paper 2 Structured Questions 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, PDG and register number on all the work you hand in. Write in dark blue or black pen. You may use a 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. 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 Examiner’s Use 1 2 3 4 5 Total This document consists of 20 printed pages. AJC Prelim 2012 9647/02/H2 [Turn over

2 AJC Prelim 2012 9647/02/H2 1 Planning (P) Suppose you are given a solution containing Zn2+, Al3+, Cl– and I– ions. You are also provided with the following: reagents apparatus · NaOH(aq), · NH3(aq), · HNO3(aq), · HCl(aq), · AgNO3(aq) and · distilled water · test tubes, · filter funnel and · filter paper (a) (i) Name the reagent, from the list provided, that can be used to convert both th e Cl– and I– ions to precipitates. ……………………………………………………………………………………………………... (ii) Name another reagent, from the list provided, that can be used to dissolve one of the precipitates formed in (a)(i). ………………………………………………………………………………… …………………... [2] (b) Using the reagents you have identified in (a), you are to devise a sequence of steps, by which the halides in the mixture could be separated such that each halide is present in a separate precipitate. In your plan, you need to include details on the reagents you will use, expected observations and state the location of each anion (i.e. in a solution or precipitate) after each step. You may present your answer in the form of a table or flow chart. [2]

3 AJC Prelim 2012 9647/02/H2 [Turn over (c) A small amount of dilute nitric acid is usually added before the addition of the reagent you have chosen in (a)(i). Suggest a reason why this is done. ……………………………………………………………………………………………………………. ……………………………………………………………………………… ……………………………. [1] (d) One of the cations present in the above mixture, Zn2+ or Al3+, can be removed as a precipitate, on reaction with excess of either NaOH(aq) or NH3(aq). Identify the reagent to be added in excess and which cation, Zn 2+ or Al3+, can be removed as a precipitate. Explain your answer using relevant equations. Reagent to be added in excess ………………………………………………………………………. Cation precipitated ……………………………………………………………………………………... Explanation…………………………………………………………………… …………………………. ……………………………………………………………………………………