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Université d’Ottawa · University of Ottawa Faculté des science Faculty of Science Chimie Chemistry CHM 1301 and CHM 1311 B DATE: December 14, 2009 Dr. Rashmi Venkateswaran 9:30 am TIME: 3 hours Page 1 of 20 FULL STUDENT NAME: (Print) _______________________________________ STUDENT NUMBER: ______________________________________________ COURSE CODE: (Please circle) CHM 1301 CHM 1311B INSTRUCTIONS: 1. Write your answers on the exam. Please BOLD or HIGHLIGHT your final answer. 2. You are allowed to use electronic calculators during the exam (TI 30X, TI 34, TI 36). 3. Equations and constants are given on pages 18 and 19. A periodic table of the elements is included (page 20). 4. Use the correct number of significant figures at all times. 5. Marks allotted to each question are shown in brackets. The exam is out of 100. 7. Use the back of sheets for rough work. Three extra (blank) pages (15, 16 and 17) have also been included. 8. You are advised to read through the exam paper before you begin to write. Answer first those questions that you can do right away, proceeding to more difficult questions thereafter. Allow about ten minutes near the end of the exam period to read quickly through your answers, checking for obvious errors. Quest. 1 2 3 4 5 6 7 8 9 10 Marks /10 /10 /10 /10 /10 /10 /10 /10 /10 /10 /100 page 2 of 20 (10) 1. The human eye contains a molecule called 11-cis-retinal that changes conformation when struck with light of sufficient energy. The change in conformation triggers a series of events that results in an electrical signal being sent to the brain. The minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164 kJ/mol. Calculate the longest wavelength visible to the human eye. [2] (b) A green leaf has a surface area of 2.50 cm2. If solar radiation, having an average wavelength of 504 nm is 1.00 x 103 W/m2, how many photons strike the leaf every second? (1 W = 1 J/s) [3] (c) How many photons at 660 nm must be absorbed to melt 5.0 x 10 2 g of ice? It takes 334 J to melt 1 g of ice at 0°C. [3] (d) What is the velocity of an electron emitted by a metal whose threshold frequency is 2.25 x 1014 s-1 when it is exposed to visible light of wavelength 5.00 x 102 nm? [2] page 3 of 20 (10) 2. A 5.00 L vessel contains 25.0 g PCl3 and 3.00 g of O2 at 15.0 °C. The vessel is heated to 200.0 °C and the contents react to give POCl3. What is the final pressure in the vessel assuming that the reaction goes to completion and that all reactants and products are in the gas phase? [6] If 26.8 g of POCl3 is actually produced, what is the percent yield of the reaction? [4] page 4 of 20 (10) 3. Sulfur reacts with fluorine to form a pair of neutral molecules, SF4 and SF6, that in turn form positive and negative ions, SF3+ and SF5-. (a) Draw the Lewis structures of each species above. Show your reasoning and all your work. [2] (b) Using VSEPR, determine the geometry and shape of each species. [4] (c) Determine the formal charges on all the atoms in the structures in (b). [2] (d) What are the major bond angles in each species likely to be? [2] page 5 of 20 (10) 4. Adiponitrile, a key intermediate in the manufacture of nylon, is made industrially by an electrolytic process that reduces acrylonitrile: Anode: 2 H 2O → O 2 + 4 H + + 4 e - Cathode: 2 CH2CHCN + 2 H+ + 2 e- → NC(CH2)4NC Acrylonitrile adiponitrile i) Write the overall balanced cell reaction. [1] ii) What mass of adiponitrile is produced in 10.0 h in a cell that has a constant current of 3.00 x 103 A? [3] iii) What volume of O2 at 740. mm Hg and 25.0 °C is produced as a bypr

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