Download Potassium Permanganate - Inorganic Chemistry - Exam and more Exams Inorganic Chemistry in PDF only on Docsity! Ollscoil na hÉireann, Gaillimh National University of Ireland, Galway Autumn II Examinations, 2011/2012 Exam Code(s) 2BS1, 2BY1, 2EH1, 2EV1, 2BPP1, 2BPC1 Exam(s) Module Code(s) CH204 Inorganic Chemistry Module(s) Paper No. Repeat Paper Special Paper External Examiner(s) Professor K. Molloy Internal Examiner(s) Dr. A. Erxleben, Dr. T. Higgins Instructions: Answer 4 questions. Answer one question from each section. All questions carry 25 marks distributed as shown. Leave the first page of the Answer Book blank and list on it clearly the numbers of the questions attempted. Duration 2 Hr. No. of Answer books Requirements: Handout MCQ Statistical Tables Graph Paper Log Graph Paper Other Material log tables with periodic table No. of Pages 4 Following this page Department(s) Chemistry Section A Answer one question from this section 1. Answer each of the following: (a) Identify x, y, A, B and C in the following equations (i) KMnO4 + x HCl A + KCl + 4 B + y C (ii) x K2CrO4 + y HCl A + y B + C [5 marks] (b) Write down the formulae of the following compounds: (i) Potassium permanganate (ii) Cupric hydroxide (iii)Ferrous sulfate (iv) Ferric chloride [8 marks] (c) Potassium iodide and HCl are added to a potassium chromate solution. A few drops of this solution are shaken with 2 cm3 of xylene. Explain (with reasons) what you expect to observe. [6 marks] (d) Suggest (with explanations) a method to determine the individual concentrations of Zn2+ and Mg2+ ions in a solution of ZnCl2 and MgCl2 in dilute HCl. ` [6 marks] 2. Answer each of the following: An iron oxalate complex of composition [Fe(C2O4)].xH2O was prepared and the iron, oxalate and water content was determined by titration: 0.199 g of the iron complex were dissolved in 30 cm3 dilute H2SO4 and titrated with 0.0198 M KMnO4 solution. The end-point was 37.1 cm3. Then 2 g of zinc dust were added and the mixture was boiled for 15 min. The solution was filtered and the filtrate was titrated again with 0.0198 M KMnO4 solution. 12.3 cm 3 were required for the titration. (a) Explain what is happening in this experiment. [6 marks] (b) Using the titration data confirm that the Fe:oxalate ratio is 1:1 in the complex. [13 marks] (c) Calculate x in [Fe(C2O4)].xH2O. [6 marks] Equations: 2 MnO4 - + 5 C2O4 2- + 16 H+ 2 Mn2+ + 10 CO2 + 8 H2O MnO4 - + 5 Fe2+ + 8 H+ 5 Fe3+ + Mn2+ + 8 H2O Atomic weights: Fe 56; O 16; H 1 ... more on the next page
