Final Exam F22 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 103-4 Final Exam Date last revised 12/19/2022 Page 1 of 8 CHEMISTRY 103-4 Name __ Key _ ______________________________ FINAL EXAM December 19, 2022 Sec _________ TA ___________________________ INSTRUCTIONS: 1. Do not separate the pages of the exam. 2. PRINT your name, discussion 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 ( 4 ) under “Special Codes”. 4. Write your answers to the multiple-choice questions in this test booklet, 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 120 minutes. 7. When you are finished, turn in your 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 26 _________/26 question 27 _________/21 question 28 _________/12 question 29 _________/8 question 30 _________/8 _________/75 Short Answer Total Thanks for a great semester and HAPPY HOLIDAYS!!!

Chem 103-4 Final Exam Date last revised 12/19/2022 Page 2 of 8 Enter your answers to the following questions on the scantron form. Each question is worth 3 points . There is ONE best response to each question. 1. Sodium azide, NaN 3 , is an ionic compound that contains the azide polyatomic ion. What is the chemical formula of the azide ion? A. N 3– B. N – C. N 3 3– D. N 3 – E. N 2 2. Which of the following reaction types does not necessarily give a visible indication of reaction? A. Precipitation reaction B. Gas forming reaction C. Neutralization reaction D. All of the above always give visible indication of reaction 3. Which of the following 1.0-gram samples has the lowest percentage of metal? A. MgO B. LiF C. ZnI 2 D. PH 3 E. KBr 4. Which of the following salts is expected to have the highest melting point? A. LiF B. BeO C. NaCl D. KBr E. CsI 5. Which atom contains the smallest number of protons? A. 51 V B. 50 Cr C. 54 Cr D. 55 Mn E. 57 Fe 6. Which of the following aqueous solutions is the weakest conductor of electric current? A. 0.1 M HClO 4 B. 0.1 M HNO 3 C. 0.1 M H 3 PO 4 D. 0.1 M H 2 SO 4 E. All solutions will have the same conductivity 7. Choose the reducing agent in the reaction below. H + (aq) + NO 3 – (aq) + 2NO(g) + H 2 O(l)  3HNO 2 (aq) A. H + B. N C. O D. NO 3 – E. NO

Chem 103-4 Final Exam Date last revised 12/19/2022 Page 3 of 8 8. Element X is triatomic, existing as X 3 molecules. It also consists of two naturally occurring isotopes, 29 X (60% natural abundance) and 31 X (40% natural abundance). How many peaks would be expected in the soft mass spectrum of X 3 ? A. 2 B. 3 C. 4 D. 5 E. 8 9. When 25 mL of 0.10 M HCl(aq) and 25 mL of 0.10 M NaOH(aq) are mixed, an exothermic reaction occurs releasing thermal energy into the surroundings, and the resulting 50 mL solution increases in temperature. Which combination of reactants would result in a solution with the same magnitude of temperature change after their mixing? A. 10 mL of 0.10 M HCl(aq) and 10 mL of 0.10 M NaOH(aq) B. 50 mL of 0.20 M HCl(aq) and 50 mL of 0.20 M NaOH(aq) C. 100 mL of 0.20 M HCl(aq) and 100 mL of 0.20 M NaOH(aq) D. 25 mL of 0.20 M HCl(aq) and 75 mL of 0.20 M NaOH(aq) E. None of the above 10. For the following combustion reaction, where there are more gaseous products compared to reactants, what are the correct signs for Δ H and w? C 2 H 5 OH(l) + 3O 2 (g)  2CO 2 (g) + 3H 2 O(g) A. Δ H > 0 w > 0 B. Δ H > 0 w < 0 C. Δ H < 0 w > 0 D. Δ H < 0 w < 0 11. Which of the following has the largest second ionization energy? A. Li B. Na C. K D. Ca E. Mg 12. Copper has 2 stable isotopes, 63 Cu and 65 Cu. Knowing that the atomic weight of copper is 63.55, estimate the approximate percentage of 63 Cu. A. 10% B. 45% C. 55% D. 70% E. 95% 13. An aqueous solution contains either CaCl 2 or Ca(OH) 2 . Which of the following reagents can be added to distinguish between the two compounds? A. ZnCl 2 B. KOH C. AgNO 3 D. NH 4 Cl E. BaSO 4

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