Technical University of Mombasa Chemistry for Engineers Past Paper Dec 2016 PDF

TECHNICAL UNIVERSITY OF MOMBASA FACULTY OF APPLIED AND HEALTH SCIENCES DEPARTMENT OF PURE & APPLIED SCIENCES UNIVERSITY EXAMINATION FOR: BACHELOR OF SCIENCE IN MEDICAL ENGINEERING BACHELOR OF TECHNOLOGY IN...

TECHNICAL UNIVERSITY OF MOMBASA FACULTY OF APPLIED AND HEALTH SCIENCES DEPARTMENT OF PURE & APPLIED SCIENCES UNIVERSITY EXAMINATION FOR: BACHELOR OF SCIENCE IN MEDICAL ENGINEERING BACHELOR OF TECHNOLOGY IN MEDICAL ENGINEERING ACH 4150 : CHEMISTRY FOR ENGINEERS END OF SEMESTER EXAMINATION SERIES: DECEMBER 2016 TIME: 2 HOURS DATE: Pick Date Dec 2016 Instructions to Candidates You should have the following for this examination -Answer Booklet, examination pass and student ID This paper consists of FIVE questions. Answer question ONE (Compulsory) and any other TWO questions. Do not write on the question paper. Question ONE (a) Assign oxidation numbers to the underlined elements in the following compounds and ion; (i) H3PO4 (ii) NaBH4 (iii) PtCl62- (3 marks) (b) Give any THREE assumptions of Bohr’s theory of the structure of the H atom. (3 marks) (c) 34.5 ml of a KHCO3 solution neutralises 25 ml of a 0.25M HCl solution. (i) Write a balanced equation of the neutralisation reaction (1 mark) (ii) Calculate the concentration of the KHCO3 solution. (3 marks) (d) For the reaction H2O2 + Fe2+ Fe3+ + H2O (i) Write the oxidation and reduction half reactions (2 marks) ©Technical University of Mombasa Page 1 of 3  (ii) Balance the reaction in acidic medium, showing all steps in balancing. (7 marks) (e) (i) Briefly describe the characteristics of an amphoteric oxide. (1 mark) (ii) Using appropriate reaction equations, show why Al2O3 is an amphoteric oxide. (4 marks) (f) For an electronic transition from the n = 5 to n = 3 energy levels in a hydrogen atom; (i) Calculate the energy of the emitted photon (3 marks) (ii) Calculate the wave number of the emitted photon (3 marks) (RH = 2.18 x 10-18 J; C = 2.99 x 109 ms-1; h = 6.63 x 10-34 Js). Question TWO (a) State the Pauli Exclusion principle. (1 mark) (b) State Hunds rule. (1 mark) (c) Provide unique quantum numbers for the valence electrons in the C (Z=6) atom. (4 marks) (d) Write electron configurations for the following elements and ions, (i) Be (Z=4) (ii) P-3 (Z=15) (iii) Cr2 (Z=24) (iv) N (Z=7) (4 marks) (e) Explain how water can be purified by ionic exchange. (8 marks) (f) Provide TWO characteristics of the H atom as a Group I and Group II element of the Periodic table. (2 marks) Question THREE (a) H-1 and Li+ are isoelectronic. Explain the difference in radii of the two species. (3 marks) (b) The 1st and 2nd Ionisation energies of Na are 495.9 and 4,560 kJ mol-1, and those of Mg are 738.1 and 1,450 kJ mol-1, respectively. Explain the differences in the ionisation energies. (8 marks) (c) Two atoms have electron configurations 1s2 2s2 and 1s2 2s2 2p1. The 1st ionisation energies of the two atoms are 801 and 899 kJ mol-1. Match each of the ionisation energies with the respective atom. Explain the choice. (6 marks) (d) Explain the low electron affinity of Nitrogen (electron affinity ≈ 0). (3 marks) ©Technical University of Mombasa Page 2 of 3 Question FOUR (a) State Lé Chatelier’s Principle (1 mark) (b) With initial concentrations of [H2]0 = 0.86 M, [N2]0 = 0.65 M and [NH3]0 = 0.45 M, and value of Kc = 9.6 at 375 °C, the synthesis of ammonia is given by the reaction; N2(g) + 3H2(g) 2NH3(g) (i) Calculate the reaction quotient Qc, and determine the direction of the reaction. (5 marks) (ii) Explain the changes in the concentration of the reactants and product. (4 marks) (c) Calculate the pH of a 0.35 M solution of NH4Cl, given Kb = 1.8 x 10-5. (10 marks) Question FIVE (a) Calculate the pH of a buffer solution made from 35.0 g of CH3COOH and 25.6 g of CH3COONa in 1.0 l of solution. Given Ka = 1.8 x 10-5. (6 marks) (b) Calculate the quantity of CaCO3 in grams that will dissolve in 1,000 ml of 0.10 M Ca(NO3)2; given Ksp = 8.7 x 10-9. [Atomic masses: N = 14, C = 12, O = 16, Ca = 40] (8 marks) (c) Highlight the processes associated with nitrogen fixation. (6 marks). ©Technical University of Mombasa Page 3 of 3