Midterm1-key

# Midterm1-key - Surname(lastname):_ Givenname(firstname):_...

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Surname (last name):_______________________________ Given name (first name):________________________________ Student number:______________________ Lab Section:___________________________ Lab TA: __________________________________ Course(circle one): 1311 B      or       1301 Chemistry 1311B/1301 Test 1 October 4, 2007 Please keep your work covered and keep your eyes on your own paper! Cheating or any appearance of cheating will result in an F in the course and possible expulsion from the University. There are 11 pages in this exam.  A periodic table, formula sheet and the solubility rules  are provided.  You may rip these 3 pages off of the exam and use them to cover your  work. Any scratch work should be on the back of the exam pages and should be handed in  with your exam. Please show all work to receive partial credit. You have 80 minutes to complete the exam. For each question, please write your final answer in the space provided .

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1. Elemental  analysis  of an  organic  liquid  compo s e d  of carbon,  hydrogen  and  nitrogen,  C x H y N z with a fishy odour gives the following elemental mass percentages:  C 71.22 %; N 13.84 %.  Vaporization of 250 mg of the compound in a 150 mL bulb at 150 C give a pressure of 435  torr.   a) (5 points) Determine the empirical formula for this compound. b) (5 points)What is the molecular formula? 100g sample C 71.22g, 12 g/mole moles: 71.22/12 = 5.935 moles N 13.84 g, 14 g/mole: 13.84/14 = 0.9886 moles H: 100g-71.22g-13.84g = 14.94 g, 1g/mole: 14.94/1 = 14.94 Divide each by smallest number of moles in hopes of getting whole numbers: C 5.935 moles/0.9886=6.0 N 0.9886 moles/0.9886 = 1 H: 14.94/0.9886=15.1 C 6 H 15 N Empirical Formula: ___  C 6 H 15 N_ ______________ Mass = 250 x 10
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## This note was uploaded on 01/17/2010 for the course CHM BIO1130 taught by Professor Houseman during the Fall '09 term at University of Ottawa.

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Midterm1-key - Surname(lastname):_ Givenname(firstname):_...

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