CH116_PracticeExam3Key

CH116_PracticeExam3Key - Name Last 5 digits of Student...

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Unformatted text preview: Name _____________________________________ Last 5 digits of Student Number: XXX – X ___ – ___ ___ ___ ___ Chem 116 Sample Examination #3 This exam consists of eight (8) pages, including this cover page. Be sure your copy is complete before beginning your work. If this test packet is defective, ask for another one. Copies of the “Periodic Table” and the “Table of Acids and Bases and K a Values” are attached at the back of the exam. You may remove these and use the back sides of these tables as scratch paper. No work on scratch paper will be graded or collected. The following information may be useful: Constants of nature E q u a t i o n s K w = 1.0 u 10 –14 at 25 ºC pH = – log [H 3 O + ] DO NOT WRITE BELOW THIS LINE Part I: Ques tion s 1-6 Ques tion 7 Ques tion 8 Ques tion 9 _________ (maximum 24) _________ (maximum 4) _________ (maximum 6) _________ (maximum 10) Part II: Ques tion 1 Ques tion 2 Part III: Lab ques tion Extr a credit _________ (maximum 20) _________ (maximum 20) _________ (maximum 16) _________ (maximum 4) Total (out of 100) KEY Disclaimer: This is a copy of a typical Exam 3 given in Chem 116 during the academic year. Your test will be different. This test is being posted to give you a sense of the format, style, scope and level of a typical test on this material. This test may have questions on topics that may not be covered on your exam. Moreover, your test may have questions on topics not covered in this practice exam. Posting this test in no way limits the format, style, scope and level of the test that you will take. Do not limit your preparation to the material in this practice exam. N a m e _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ p a g e 2 o f 9 Part I. Multiple-Choice or Short Response Points possible on each question are indicated in curly braces {…}. This part of the exam (Part I) is worth 44% of the exam grade. 1. {4 pts} When the polyprotic acid, oxalic acid (H 2 C 2 O 4 ), is added to water, it undergoes the following two-step dissociation process: H 2 C 2 O 4 + H 2 O ' HC 2 O 4 – + H 3 O + K a1 = 5.90 u 10 –2 HC 2 O 4 – + H 2 O ' C 2 O 4 2– + H 3 O + K a2 = 6.40 u 10 –5 The majority of the hydronium ion concentration, [H 3 O + ], is produced in A) The first dissociation step B) The second dissociation step C) The amount that was present in the pure water prior to adding the oxalic acid D) There is not enough information to tell 2. {4 pts} A sample of 0.0200 moles of propanoic acid is added to 1.00 L of water. When the acid is fully dissolved and the solution comes to equilibrium, the solution is found to have a pH of 3.30. What is the value of K a for propanoic acid?...
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CH116_PracticeExam3Key - Name Last 5 digits of Student...

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