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[Exam Tutorial] Chem 112 2012 Midterm Questions

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CHEM 112
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University of Saskatchewan Department of Chemistry CHEMISTRY 112.3 Midterm Examination February 13, 2012 (6 PM – 8 PM) VERSION M3 Last Name (please print clearly!)____________________________________________ Given Name (please print clearly!)_____________________________________________ Student Number Signature___________________________________ Please indicate your section: Section 01 MWF 9:30 AM Dr. A. Grosvenor Section 03 TR 10:00 AM Dr. P. Ahiahonu Section C15 North West Dr. R. Catton INSTRUCTIONS - PLEASE READ THIS FIRST! 1. This is a closed-book examination. A data-sheet with a Periodic Table is attached to the last page of this examination paper (you can remove this page from the booklet for convenience) 2. Simple scientific calculators are permitted. Alphanumeric calculators and those capable of storing equations are not permitted. Cell phones, personal digital assistants, electronic dictionaries, etc. are not allowed. No equations may be stored in memory of electronic devices. 3. This examination paper has 10 pages, including the data sheet. To ensure that your copy is complete and to become familiar with the questions, please read through the entire examination before you answer any questions. 4. You can use the backside of the pages as scratch paper. 5. A total of 100 marks can be obtained. Each of the 40 questions will be weighted with 2.5 marks each. 6. Please fill out the top of this paper and the top of the blue op-scan sheet. Print your name and code your student number in soft pencil. 7. Answer these questions by circling the response on this paper AND by filling out the corresponding response on the blue opscan sheet USING A SOFT-LEAD PENCIL ONLY. No deductions will be made for incorrect answers, but multiple answers will be treated as NO answer. 8. If you change your mind, erase the incorrect answer carefully from the blue optical scan sheet. In the event of a discrepancy, the response on the opscan sheet will count. 9. HAND-IN ALL of your material (question sheet and computer sheet) 2 1. The accelerat2on due to gravity at a certain location is 32.2 ft/s , what is its numerical value if it is expressed in terms of m/h ? (1 ft (foot) = 30.48 cm; s = second; h = hour) 4 2 A. 3.53 × 10 8/h 2 B. 1.27 × 10 m/h C. 4.17 × 10 m/h 2 9 2 D. 3.95 × 10 m/h E. 8.56 × 10 m/h 2 2. How many significant figures should be shown for the result of the following mathematical operation? A. 3 B. 4 C. 1 D. 2 E. 5 3. An acetaminophen suspension for infants contains 80 mg of acetaminophen per 1.0 mL of liquid (80 mg/1.0 mL). The recommended dose is 15 mg/kg body weight. How many mL of this suspension should be given to an infant weighing 6.35 kg? A. 1.0 mL B. 0.19 mL C. 1.191 mL D. 1.2 mL E. 0.76 mL 4. In 2009, the Greater Toronto area air had carbon monoxide (CO) levels of 12.0 L of CO per 1.00 x 10 L of 6 air. An average human inhales about 0.450 L of air per breath and takes about 25 breaths per minute. How many milligrams of carbon monoxide does the average person inhale in a 12 hour period? Assume that carbon monoxide has a density of 1.20 g/L. A. 120 mg B. 117 mg C. 116.5 mg D. 110 mg E. 11.7 mg 5. A uniform sphere has a radius (R) of 18.0 mm and a density of 2.041 g/cm , what is the value of its mass in grams? 3 Given: volume of a sphere = R A. 49.86 g B. 50 g C. 49.860 g D. 49 g E. 49.9 g 2 6. How many protons (p), electrons (e), and neutrons (n) are there in ? A. 13 p, 10e, and 14 n B. 27 p, 13e, and 27 n C. 13p, 13e, and 14n D. 13p, 14e, and 13 n E. 13p, 13e, and 13n 7. During an experiment, a mixture of two organic liquids (having different boiling points) was separated using a distillation apparatus. The solution was heated by burning natural gas in a Bunsen burner and resulted in the component with the lowest boiling point evaporating first. The flame of the burner was kept too close to the bottom of the flask and some of the organic mixture decomposed into a black carbon deposit on the inside of the flask. Identify the changes involved during this distillation as being chemical or physical. A. Evaporation = chemical; Decomposition = chemical; Burning of natural gas =chemical B. Evaporation = physical; Decomposition = physical; Burning of natural gas = chemical C. Evaporation = physical; Decomposition = chemical; Burning of natural gas = chemical D. Evaporation = physical; Decomposition = physical; Burning of natural gas = physical E. Evaporation = chemical; Decomposition = physical; Burning of natural gas = physical 8. What is the mass number of an iron atom that has 28 neutrons? A. 26 B. 28 C. 45 D. 53 E. 54 o 9. The density of water is 1.00 g/mL at 4 C. How many water molecules are present in 2.56 mL of water at this temperature? A. 8.56 × 10 21 20 B. 6.022 × 10 C. 6.022 × 10 23 22 D. 8.56 × 10 23 E. 2.011 × 10 10. The “lead” in lead pencils is actually almost pure carbon, and the mass of a period mark made by a lead pencil is about 0.0001g. How many carbon atoms are in the period? A. 6 × 10 atoms 23 B. 6.022 × 10 atoms C. 5 × 10 atoms D. 5 × 10 atoms 23 E. 3.011 × 10 atoms 3 11. The fictional isotope Xium-60 has an atomic mass of 60.15 units while Xium-70 has an atomic mass of 70.16 units. The average mass of Xium is 69.41 units. What is the fractional abundance of Xium-70? Assume that only these two isotopes of Xium occur in nature. A. 9.25 B. 1.95 C. 0.875 D. 0.925 E. 0.0925 12. Which of the following is the definition of the value of Avogadro’s constant. A. The number of carbon atoms in exactly 1 g of carbon-12 B. The number of hydrogen atoms in exactly 1 g of hydrogen-1 C. The number of hydrogen atoms in exactly 12 g of hydrogen-1 D. The number of carbon atoms in exactly 12 g of carbon-12 E. None of the above 13. Choose the incorrect statement: A. An anion is a positive ion B. A molecule is a group of atoms bonded together that exists as an entity C. Ionic compounds result from combinations of metals and non-metals. D. The empirical formula is the simplest formula of the ratio of atoms. E. The molecular formula is the listing of the atoms in an actual molecule. 14. Which of the following elements would have chemical properties that are most similar to those of Gallium? A. Gadolinium B. Germanium C. Zinc D. Aluminum E. All must have the same properties because all these elements are metals 15. How many hydrogen atoms are there in 12.4 g of Al (HPO2) ? 4 3 A. 4.39 x 10 22 22 B. 6.55 x 10 22 C. 6.07 x 10 D. 1.09 x 10 22 E. 1.32 x 10 23 16. Which of the following species contains the greatest number of S atoms? A. 30 mL of CS (d2nsity = 1.2 g/mL) B. 0.14 mol S 8 C. 0.30 mol SO 2 D. 45 g S O 2 E. They all contain the same number of S atoms 4 17. A compound is found to have the following percent mass composition: 38.7% K, 13.8% N, 47.5% O. What is the empirical formula of the compound? A. K N2 3 B. KNO 2 C. KNO 3 D. K N2O 2 3 E. K 2O 2 18. Choose the incorrect chemical formula and name combination. A. SiO ; silicon dioxide 2 B. Cu 3PO )4 2copper(II) phosphate C. HClO; hypochlorous acid D. CaH ;2calcium hydroxide E. AlCl 3 aluminum chloride 19.The complete combustion of a sample of a pure organic compound containing C and H yielded 0.973 g of CO a2d 0.299 g of H O. 2he empirical formula of this compound is: A. C H2 3 B. C H3 5 C. C H4 6 D. C H5 8 E. C 6 9 20. The name of which compound ends in “ate”? A. HNO 3 B. Na 2rO 4 C. Na 2 D. NaClO 2 E. H 2O 3 21. The molecular formula for a sugar molecule is C H O12 W22t11s the mass percent of C in the molecule? A. 42.12 % B. 67.88 % C. 2.37 % D. 26.67 % E. 8.34 % 5 22. What is the sum of all stoichiometric coefficients when the following chemical equation is balanced? H 2O 3(aq)+ Al(OH) 3(aq)  Al (2O ) 3 3(aq)+ H O2 (l) A. 4 B. 5 C. 12 D. 14 E. 11 23. For the following reaction, calculate the mass of carbon dioxide (CO 2(g) produced from the combustion of 44.0 g of CH 4(g) CH 4(g) 2O 2(g) CO 2(g)+ 2H 2 (g)(Note: assume that O 2(g)is present in excess.) A. 118 g B. 60.4 g C. 87.8 g D. 121 g E. 44.0 g 24. Balance the following chemical equation and identify the correct stoichiometric coefficients. a C H3 6(l)+ b O 2(g)→ c CO 2(g)+ d H O 2 (g) A. a = 2; b = 9; c = 6; d = 6 B. a = 1; b = 2; c = 2; d = 1 C. a = 1; b = 4.5; c = 3; d = 3 D. a = 3; b = 12; c = 12; d = 8 E. a = 4; b = 18; c = 12; d = 12 25. For the combustion reaction of CH , determine which molecule represents the limiting reagent if 4.0 mols 4(g) of CH 4(g)reacts with 5.5 mols of O 2(g)o form 2.75 mols of CO 2(g) A. All reagents are present in the proper proportions (i.e., none are limiting) B. CH 4 C. CO 2 D. O 2 E. H 2 26. For the following reaction, calculate the number of mols of SrCl 2(aq)that would be required to form 40.0 g of Sr3(PO 4 2(s) 3SrCl 2(aq) 2Li 3O 4(aq) Sr 3PO ) 4 2(s) 6L
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