NYGH 2022-S3EOY-IP Chem P2

Class Register Number Name End-of-Year Examination 2022 Secondary 3 IP CHEMISTRY Paper 2 1 hour 45 minutes Wednesday 5 October 1030 – 1215 READ THESE INSTRUCTIONS FIRST Write your name, register number and class in the spaces at the top of this page. Write in dark blue or black pen. You may use a pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid / tape. Section A Answer all questions in the spaces provided. You are advised to spend no longer than 1 hour on Section A, and no longer than 45 minutes on Section B. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is on page 11. The use of an approved scientific calculator is expected, where appropriate. Section A (40 marks) Section B (30 marks) Total (70 marks) This document consists of 10 printed pages and 2 blank pages. Setter(s): OWJ/CHG NANYANG GIRLS' HIGH SCHOOL [Turn over A

2 Setters: OWJ/CHG Chemistry Paper 2 Section A (40 marks) Answer all questions. Write your answers in the spaces provided. A1 Epsom salt is a bitter-tasting salt with the chemical formula, MgSO 4.nH2O. It is widely used as bathing salt to relieve body aches. (a) (i) Suggest the chemical formulae of two suitable reactants for making aqueous magnesium sulfate, stating which one is in excess. [2] (ii) State how the excess reactant can be removed from aqueous magnesium sulfate. [1] (iii) State the most suitable method by which Epsom salt can be obtained from aqueous magnesium sulfate. [1] (b) A sample of Epsom s alt weighing 4.93 g initially was strongly heated in an evaporating dish until it decomposed to form the anhydrous salt, MgSO4. The following graph was obtained. (i) State the minimum temperature required to decompose the Epsom salt into the anhydrous salt. [1] oC (ii) Calculate the relative molecular mass of anhydrous magnesium sulfate, MgSO4. [1] mass of solid / g temperature / oC 4.93 2.41 250 65

3 Setters: OWJ/CHG Chemistry Paper 2 [Turn Over (iii) Calculate the number of moles of MgSO4.nH2O in 4.93 g of Epsom Salt. [1] (iv) Using the information in the graph and answer in (b)(iii), derive the exact chemical formula of Epsom salt, showing all necessary working. [3] Total [10]

4 Setters: OWJ/CHG Chemistry Paper 2 A2 A sample of X contains three substances, A, B and C. (a) In an experiment, a student conducting the experiment accidentally dripped a drop of sample X into the solvent. The student observed that the colour of sample X spread t