MI_H2_CHEM_P2 Prelim

Class Adm No Candidate Name: This document consists of 19 printed pages and 1 blank page. [Turn over 2014 Preliminary Examination II Pre-university 3 H2 CHEMISTRY 9647/02 Paper 2 Structured Questions Friday, 19 Sep 2014 2 hours Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces provided at the top of this page. Write in dark blue or black pen in the spaces provided. 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. 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. For Examiner’s Use 1 /12 2 /18 3 /11 4 / 9 5 /22 Total /72

2 1 Planning (P) For Examiner’s Use In metal displacement reactions, a more reactive metal will displace a less reactive metal from a solution. Copper, silver and gold appear as elements in the earth due to their poor reactivity with the environment. These metals are easy to extract. You ar e required to plan an experiment to determine the enthalpy change of a metal displacement reaction between zinc and copper( II) sulfate solution. Zinc reacts with aqueous copper(II) sulfate as shown by the equation below. Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s) The reaction is exothermic and spontaneous, requiring only a few minutes to go to completion. You are provided with the following chemicals  Zinc powder,  0.8 mol dm-3 copper(II) sulfate, CuSO 4 as well as apparatus commonly found in the laboratory. (a) State the observations when the reaction goes to completion. ………………………………………………………………………………………………… ………………………………………………………………………………………………… [1] (b) Using the information above, write a plan to describe how you would determine the enthalpy change of the reaction between zinc and copper(II) sulfate. Your plan must include  a suitable mass of zinc to be used, and your justifications for choosing this mass,  the volume of copper(II) sulfate solution to be used,  detailed procedures of the experiment you would perform. Include details of the apparatus you would use, and  the precautions you would take to minimise heat loss.

3 [Turn over ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………