178Exam3KeyS07

178Exam3KeyS07 - DR. JESUDOSS KINGSTON DR. JOE BURNETT...

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Unformatted text preview: DR. JESUDOSS KINGSTON DR. JOE BURNETT SPRING 2007 THIS EXAM CONSISTS OF 16 QUESTIONS ON 8 PAGES CHEM 178 HOUR EXAM III April 11, 2007 NAME______________________ RECIT. INSTR.______________ RECIT. SECT._______________ GRADING Teaching Assistants and Recitation Sections PAGE POINTS SCORE Name Sections Time 2 3 4 5 6 7 TOTAL 12 pts 18 pts 20 pts 19 pts 20 pts 13 pts 102 pts ________ ________ ________ ________ ________ ________ David Ackerman Wei Huang Andrew Lantz Michael Murphy Sean Nedd Beth Prince Rafael Lopes Quirino Suzanne Sander Yongchao Su Aaron West 1, 11 4, 20 14, 15 5, 8 6, 13 3, 12 10, 16 7, 17 2, 9 18, 19 8:00, 9:00 10:00, 9:00 11:00, 12:10 11:00, 12:10 11:00, 10:00 9:00, 10:00 2:10, 12:10 12:10, 1:10 9:00, 1:10 2:10, 3:10 QUESTIONS ARE WRITTEN ON BOTH SIDES OF EACH PAGE. THERE IS A PERIODIC TABLE, EQUATIONS, AND CONSTANTS ON THE LAST PAGE. YOU MAY REMOVE THIS PAGE FOR SCRATCH PAPER. THE ANSWER KEY TO THIS EXAM WILL BE POSTED ON BULLETIN BOARD #6 IN THE HALLWAY EAST OF ROOM 1002 GILMAN AND ON THE CHEM 178 WEBSITE. SHOW ALL WORK. ANSWERS SHOULD INCLUDE APPROPRIATE UNITS AND CONTAIN THE CORRECT NUMBER OF SIGNIFICANT FIGURES. CHEM 178 FINAL EXAM MONDAY, APRIL 30, 7:00-9:00 P.M. SAME ROOMS AS HOUR EXAMS NO CHANGE Answer Key 2 1. (3 pts) Consider the indicators shown in the table. Which indicator is most appropriate for the titration of a weak base by a strong acid? a) thymol blue b) bromothymol blue c) phenolphthalein d) alizarin yellow e) all of the above would be appropriate f) none of the above would work. 2. (3 pts) The figure to the right shows the titration of 0.10 M H 3 PO 4 by 0.10 M NaOH. The principle species present at point X are a) H 3 PO 4 and HPO 4 2 b) H 2 PO 4 and HPO 4 2 c) PO 4 3 and HPO 4 2 d) H 2 PO 4 and H 3 PO 4 e) H 3 PO 4 , HPO 4 2 , and PO 4 3 f) H 3 PO 4 , H 2 PO 4 , HPO 4 2 , and PO 4 3 3. (3 pts) In the titration of 50.0 mL of 0.100 M benzoic acid (a monoprotic acid) with 50.0 mL of 0.100 M NaOH, the properties of the solution at the equivalence point correspond exactly to the properties of a) a 0.10 M sodium solution b) a 0.050 M sodium benzoate solution c) a 0.050 M sodium hydroxide solution d) a 0.050 M benzoic acid solution 4. (3 pts) When a system is at equilibrium, ________________. a) the forward and the reverse processes are both spontaneous b) both forward and reverse processes have stopped c) the forward process is spontaneous but the reverse process is not d) the process is not spontaneous in either direction e) the reverse process is spontaneous but the forward process is not. indicator pH range for color change thymol blue 1 3 bromothymol blue 6 8 phenolphthalein 8 10 alizarin yellow 10 12 mL of NaOH pH X 3 5. (8 pts) 0.089 M HNO 3 is used to titrate 45.0 mL of a 0.12 M NH 3 solution. Calculate the volume in mL of HNO 3 needed to reach the equivalence point. For full credit, show all work, use units, and report your answer to the correct number of significant figures. your answer to the correct number of significant figures....
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This test prep was uploaded on 03/26/2008 for the course CHEM 178 taught by Professor Stoffregen during the Spring '06 term at Iowa State.

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178Exam3KeyS07 - DR. JESUDOSS KINGSTON DR. JOE BURNETT...

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