Exam 1 Fall 2023 KEY

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University of Wisconsin, Madison *

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103

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Chemistry

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Jan 9, 2024

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Chem 103 MWF Exam 1 Date last revised 10/8/2023 Page 1 of 10 CHEMISTRY 103 MWF Name _________________________________ EXAM 1 October 4, 2023 Disc _________ TA ______________________ INSTRUCTIONS: 1. Do not separate the pages of the exam. 2. PRINT your name, section number, and TA’s name at the top of this page NOW . 3. The scantron form is machine-scored and must be filled out using a #2 pencil. PRINT your last name and the first 5 letters of your first name on the scantron form as it appears in Canvas, then fill in the circles corresponding to the letters in your name. Write your student ID number under “Identification Number”, and fill in the circles. Write your lecture number under “Special Codes”. 1 = Zelewski 8:50 AM 2 = Zelewski 11:00 AM 3 = Zhou 1:20 PM 4 = Brunold 3:30 PM 4. Write your answers to the multiple choice questions in this test booklet so you have a record of what your answer is, then transfer your answers to the scantron form. Only the scantron form will be graded. 5. Answer the remaining short answer questions directly in the space provided in this exam. Report all numerical answers with the correct number of significant figures and units. Show all relevant work to receive full credit. 6. Complete the following exam by yourself. You will be given 75 minutes. 7. When you are finished, turn in your notecard, reference sheet, scantron form and exam. 8. Read and sign the Honor Code statement. Honor Code: I affirm that I will not give or receive any unauthorized help on this exam, and that all work will be my own. Signature question 13 _________/14 question 14 _________/13 question 15 _________/9 question 16 _________/16 _________/52 Short Answer Total KEY

Chem 103 MWF Exam 1 Date last revised 10/8/2023 Page 2 of 10 Enter your answers to the following questions on the scantron form. Each question is worth 4 points. There is ONE best response to each question. 1. An atom of an unknown element X has a mass of 64 amu and 34 neutrons. What element is X? A. Se B. Zn C. Ga D. Gd E. Tb 2. Consider the following four compounds: CoCl 2 N 2 O 4 OCl 2 CaO How many of these are molecular compounds? A. 0 B. 1 C. 2 D. 3 E. 4 3. Which of the following pairs of substances will react with each other when they are combined? (i) FeCl 2 (aq) and K(s) (ii) NiSO 4 (aq) and Ag(s) (iii) AgNO 3 (aq) and Sn(s) A. Only (ii) B. Only (iii) C. Only (i) and (ii) D. Only (ii) and (iii) E. Only (i) and (iii) 4. The following diagram represents the collection of CO 2 and H 2 O molecules formed by the complete combustion of a hydrocarbon. What is the empirical formula of the hydrocarbon? A. CH B. CH 2 C. CH 3 D. C 4 H 6 E. C 4 H 12

Chem 103 MWF Exam 1 Date last revised 10/8/2023 Page 3 of 10 5. The graph below shows the numbers of neutrons versus number of protons for stable isotopes of the elements. Which of the following statements regarding this graph is FALSE ? A. This graph includes elements from period 4. B. The element with 39 protons has a stable isotope with 50 neutrons. C. This graph shows that stable isotopes tend to have more neutrons than protons. D. This graph allows us to predict the exact number of stable isotopes the element with 60 protons would have. E. The average atomic mass of elements with 30-50 protons cannot be determined from the data presented in the graph alone. 6. An area of 300 μm 2 (micrometer squared) is equal to _____ mm 2 (millimeter squared) A. 0.000003 B. 0.0003 C. 0.3 D. 300,000 E. 300,000,000 7. Which of the following statements is FALSE given the following net ionic equation? H 3 PO 4 (aq) + 3 OH – (aq) → PO 4 3– (aq) + 3 H 2 O( ℓ ) A. If all the water was evaporated, the salt remaining could possibly be Na 3 PO 4 . B. The acid, H 3 PO 4 , is a weak electrolyte. C. The cation, K + , could possibly be a spectator ion. D. This is classified as a neutralization reaction. E. This could be the net ionic equation for H 3 PO 4 reacting with Al(OH) 3 . 15 20 25 30 35 40 45 50 55 60 15 25 35 45 55 65 75 85 Number of Neutrons Number of Protons Stable Isotopes of the Elements

Chem 103 MWF Exam 1 Date last revised 10/8/2023 Page 4 of 10 8. Given 1 mole of each of the compounds listed below, which compound will have the greatest number of ions? A. AlCl 3 B. KMnO 4 C. NH 4 CH 3 COO D. Mg(ClO 4 ) 2 E. Li 2 CO 3 9. Potassium iodate, KIO 3 , is an ionic compound that contains the iodate polyatomic ion. What is the chemical formula of the iodate ion? A. O 2– B. O 3 C. O 3 – D. IO 3 – E. IO 3 2– 10. CH 3 COOH is a(n) ___. A. ionic compound that partially ionizes in water to form a small number of H 3 O + and CH 3 COO – ions. B. ionic compound that completely ionizes in water to form H 3 O + and CH 3 COO – ions. C. molecular compound that does not form any ions when added to water. D. molecular compound that partially ionizes in water to form a small number of H 3 O + and CH 3 COO – ions. E. molecular compound that completely ionizes in water to form H 3 O + and CH 3 COO – ions. 11. Consider the reaction: 2 NaI(aq) + 2 H 2 SO 4 (aq) + MnO 2 (s) → Na 2 SO 4 (aq) + MnSO 4 (aq) + I 2 (s) + 2 H 2 O( ℓ ). Which of the following statements is correct ? A. I – is oxidized and MnO 2 is the oxidizing agent. B. I – is oxidized and NaI is the oxidizing agent. C. Mn 4+ is oxidized and NaI is the oxidizing agent. D. Mn 4+ is oxidized and MnO 2 is the oxidizing agent. E. O 2– is oxidized and H 2 SO 4 is the oxidizing agent. 12. Determine the moles of Fe(s) that can be produced from the reaction of 12.3 mol Fe 2 O 3 (s) with 29.6 mol CO(g): Fe 2 O 3 (s) + 3 CO(g) → 2 Fe(s) + 3 CO 2 (g) A. 12.3 mol B. 19.7 mol C. 24.6 mol D. 29.6 mol E. 41.9 mol Make sure to enter your multiple choice answers on the scantron form!

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