MJC H2 Chem 2012 Prelim P2 QP

Calculator Model / No. Name ________________________ Class: ___________ Reg Number: ______ MERIDIAN JUNIOR COLLEGE Preliminary Examination Higher 2 ____________________________________________________________________________ Chemistry 9647 Paper 2 Structured Questions 10 September 2012 2 hours Additional Materials: Data Booklet ____________________________________________________________________________ INSTRUCTIONS TO CANDIDATES Write your name, class and register number in the spaces provided at the top of this page. Write your calculator brand and model/number in the box provided above. Answer all questions in the spaces provided on the question paper. All working must be shown clearly. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. You are reminded of the need for good English and clear presentation in your answers. FOR EXAMINER’S USE Q1 / 12 Q2 / 8 Q3 / 12 Q4 / 12 Q5 / 9 Q6 / 19 Total / 72 This document consists of 21 printed pages and 1 blank page. copyright chem dept @ meridian jc 1

copyright chem dept @ meridian jc 2 mass of solid in a saturated solutionsolubility = ×100mass of water in the saturated solution 1 Planning (P) (a) The ‘solubility’ of a substance in aqueous solution is defined as the mass of anhydrous solid that will dissolve in and just saturate 100 g of water at a fixed temperature. · A solution that is satur ated at a par ticular tempe rature is one in which no more solid may be dissolved. · A saturated solution can be recognised by undissolved solid in equilibrium with aqueous solution. · For example, a saturated solution of potassium chlor ate(V) can be represented by the equilibrium: KClO 3(s)  KClO3(aq) You are pr ovided with solid potassium chlo rate(V), KClO3, and distilled water. In addition to the standard apparatus present in a laboratory you are provided with the following materials: · evaporating basin · measuring cylinders (i) Use the information given above to plan an experiment to d escribe how you would prepare a saturated solution of potassium chlorate(V) at room temperature. ‘solubility’

copyright chem dept @ meridian jc 3 (ii) Hence, describe an experiment to determine the ‘ solubility’ of the potassium chlorate(V) prepared in (a)(i). (iii) Create specimen results for your experiment and show how you would use these results to calculate the ‘solubility’ of potassium chlorate(V) at room temperature. (iv) Identify a potential safety hazard in the experiment and state how you would minimise this risk. [7]

copyright chem dept @ meridian jc