HCI Prelim P2

NAME: _______________________________________ CT: ___________ HWA CHONG INSTITUTION C2 PRELIMINARY EXAMINATION 8872 H1 CHEMISTRY PAPER 2 18 September 2009 2 hours       INSTRUCTIONS TO CANDIDATES 1. This paper consists of 11 printed pages. You should also have a Data Booklet , a set of writing paper and a cover page for Section B. 2. Answer all questions in Section A (Structured Questions) in the spaces provided in this answer booklet. 3. Answer any two questions in Section B (Free Response Questions) on the writing paper provided. Begin each question on a FRESH sheet of writing paper. Tie your answer scripts to Section B behind the cover page provided. 4. At the end of the examination, hand in your answers to Section A and Section B SEPARATELY. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. You may use a calculator. You are reminded of the need for good English and clear presentation in your answers. FOR EXAMINER’S USE TOTAL Multiple Choice Section A (Structured) Section B (Free Response) Q1 / 8 Q5 / 20 Q2 / 16 Q6 / 20 Q3 / 8 Q7 / 20 Q4 / 8 / 30 Subtotal / 40 Subtotal / 40 110 This document consists of 11 printed pages.

HCI(College) 2009 8872/02/C2 Prelim/09 2 Section A Answer all the questions in this section in the spaces provided. 1 (a) Copper exists as 63Cu and 65Cu isotopes. The relative abundance of 65Cu is 30.8. (i) Define the term relative atomic mass. ……………………………………………………………………………………………….... ……………………………………………………………………………………………….... (ii) Calculate the relative atomic mass for copper. (iii) Complete the following table with the number of elementary particles (electrons, protons, and neutrons) that are contained in the ion for the isotope of copper. Ion protons neutrons electrons 63Cu2+ [3] (b) The hydrated double salt, A, Cu(NH4)x(SO4)y.6H2O has a Mr of 399.5. Its formula may be determined from the following experimental data. (i) 2.00 g of salt A was boiled with excess sodium hydroxide. The ammonia expelled was collected by absorption in 40.0 cm 3 of 0.500 mol dm −3 hydrochloric acid in a cooled flask. Subsequently, this solution required 20.0 cm3 of 0.500 mol dm−3 sodium hydroxide for neutralisation. Calculate the mass of ammonium ion present in 2.00 g of salt A.

3 (ii) A second sample of 2.00 g of salt A was dissolved in water and treated with an excess of barium chloride solution. The mass of barium sulfate precipitated, after drying, was found to be 2.33 g. Calculate the mass of sulfate ion in 2.00 g of salt A.