Chemistry Exam I for CHEM 1314: Reactions, Formulas, and Empirical Formulas - Prof. John G, Exams of Chemistry

Download Chemistry Exam I for CHEM 1314: Reactions, Formulas, and Empirical Formulas - Prof. John G and more Exams Chemistry in PDF only on Docsity! CHEM 1314.03 Name ________________________ Exam I John I. Gelder TA's Name ________________________ September 25, 1997 Lab Section ______________________ Please sign your name below to give permission to post, by the last 4 digits of your student I.D. number, your course scores on homework, laboratories and exams. If you do not sign no scores will be posted. __________________________________ (signature) INSTRUCTIONS: 1. This examination consists of a total of 6 different pages. The last two pages include a periodic table and some useful equations. All work should be done in this booklet. 2. PRINT your name, TA's name and your lab section number now in the space at the top of this sheet. DO NOT SEPARATE THESE PAGES . 3. Answer all questions that you can and whenever called for show your work clearly. Your method of solving problems should pattern the approach used in lecture. You do not have to show your work for the multiple choice or short answer questions. 4. No credit will be awarded if your work is not shown in problems 4a, 4d, and 4e. 5. Point values are shown next to the problem number. 6. Budget your time for each of the questions. Some problems may have a low point value yet be very challenging. If you do not recognize the solution to a question quickly, skip it, and return to the question after completing the easier problems. 7. Look through the exam before beginning; plan your work; then begin. 8. Relax and do well. Page 2 Page 3 Page 4 Page 5 TOTAL SCORES _____ _____ _____ _____ ______ (33) (27) (17) (23) (100) CHEM 1314 EXAM I PAGE 2 (12) 1. Write the chemical formula(s) of the product(s) and balance the following reactions. Identify all products phases as either (g)as, (l)iquid, (s)olid or (aq)ueous. a) calcium nitrate(aq) + sodium phosphate(aq) → b) P4(s) + O2(g) ∆ → c) C5H11OH(l) + O2(g) ∆ → d) sulfuric acid(aq) + zinc(s) → (9) 2. Perform the following calculations and give the answer to the correct number of significant figures. a) 3.1416 · (1.30)2 = b) 2.97 x 102 + 8.78 x 104 = c) 7.966 + 3.046 x 102 1 273 15 1 283.   −   = (12) 3. Complete the following table Formula M, Molar Mass    g mol m, mass of sample (gms) n, moles of sample (mol) N, number of molecules, or formula units AgS 0.0459 C7H5BiO4 1.75 x 103 C2X2H8 150. 1.50 x 1024 What is the symbol (or name) of the unknown element, X? CHEM 1314 EXAM I PAGE 5 Multiple Choice: (15 points) Print the letter (A, B, C, D) which corresponds to the answer selected. 8. ________ 9. ________ 10. ________ 11. ________ 12. ________ ONLY THE ANSWERS IN THE AREA ABOVE WILL BE GRADED. Select the most correct answer for each question. Each question is worth 3 points. 8. A series of compounds containing sodium, chlorine and oxygen have the general formula NaClOn. One of these compounds is 28.96% chlorine. What is the correct formula for this compound? A) NaClO B) NaClO2 C) NaClO3 D) NaClO4 E) NaClO5 9. Which of the following sets of substances contain the same number of electrons? A) Cl–1, Ar, Ca2+ B) F–1, Cl–1, I–1 C) Fe2+, Fe3+, Fe4+ D) O–2, Ne, Li1+ 10. Which of the following is the higher temperature? A) 230 K B) –25 ˚F C) –25 ˚C D) –40 ˚F 11. Which of the following has the greatest number of oxygen atoms? A) 0.250 moles of HNO3 B) 2.450 grams of Al2(SO4)3 C) 3.00 x 1023 molecules of H2O D) 3.00 gms CuSO4 · 5H2O 12. Which of the following has highest percentage of nitrogen by weight? A) NO B) NO2 C) N2O D) N2H4 E) Mg3N2 CHEM 1314 EXAM I PAGE 6 90 232.0 91 231.0 Th Pa 92 238.0 93 237.0 94 (244) 95 (243) 96 (247) U Np Pu Am Cm 97 (247) 98 (251) 99 (252) 100 (257) 101 (258) 103 (260) 102 (259) Bk Cf Es Fm Md LrNo 58 140.1 59 140.9 Ce Pr 60 144.2 61 (145) 62 150.4 63 152.0 64 157.2 Nd Pm Sm Eu Gd 65 158.9 66 162.5 67 164.9 68 167.3 69 168.9 70 173.0 Tb Dy Ho Er Tm Yb 37 85.47 Rb 38 87.62 Sr 39 88.91 Y 40 91.22 Zr 41 92.91 42 95.94 43 (98) 44 101.1 45 102.9 46 106.4 47 107.9 Nb Mo Tc Ru Rh Pd Ag 48 112.4 49 114.8 50 118.7 51 121.8 52 127.6 54 131.3 53 126.9 Cd In Sn Sb Te XeI 3 6.94 4 9.01 Li Be 11 22.99 12 24.30 Na Mg 19 39.10 K 22 47.88 20 40.08 Ca 21 44.96 Sc Ti 23 50.94 24 52.00 25 54.94 26 55.85 27 58.93 28 58.69 29 63.55 V Cr Mn Fe Co Ni Cu 30 65.38 31 69.72 32 72.59 33 74.92 34 78.96 36 83.80 35 79.90 Zn Ga Ge As Se KrBr 5 10.81 6 12.01 B C 8 16.00 O 9 19.00 F 7 14.01 N 10 20.18 Ne 13 26.98 14 28.09 Al Si 16 32.06 S 17 35.45 Cl 15 30.97 P 18 39.95 Ar 2 4.00 He 55 132.9 Cs 56 137.3 Ba 57 138.9 La 72 178.5 Hf 73 180.9 74 183.8 Ta W 75 186.2 76 190.2 77 192.2 78 195.1 79 197.0 Re Os Ir Pt Au 80 200.6 81 204.4 82 207.2 83 209.0 84 (209) 86 (222) 85 (210) Hg Tl Pb Bi Po RnAt 1 1.008 H IA IIA IIIA IVA VA VIA VIIA VIIIA IIBIBVIIIVIIBVIBVBIVBIIIB 1 2 3 4 5 6 7 Lanthanides Actinides Periodic Table of the Elements 87 (223) Fr 88 226.0 Ra 89 227.0 Ac 104 (261) 105 (262) 106 (263) 71 175.0 Lu Rf Db Sg 108 (265) 109 (266) 107 (262) Hs MtBh Useful Information 1 pound (lb) = 453.59237 gram (gm) 1 liter (L) = 1.056718 quart (qt) 4 qt = 1 gallon (gal) 1 inch (in) = 2.54 centimeters (cm) 1 mile = 5280 feet (ft) ˚C = 5 9(˚F – 32) density of water = 1.00 g mL K = ˚C + 273.15 average atomic mass = Σ(isotopic mass · fractional abundance) Avogadro's number = 6.022 x 1023 CHEM 1314 EXAM I PAGE 7 (3) a) Determine its molar mass. (9) b) Determine the percent by mass of each of the elements in the compound. (2) c) What is the name of the compound? (4) d) How many atoms of oxygen are in one formula unit of the compound? (4) e) How many moles of the compound are contained in 2.450 grams of Al2(SO4)3 (6) f) What mass of Na2SO4 contains the same number of formula units as 125 gms of Al2(SO4)3? d) How many moles are contained in 12.5 g of this compound? f) What is the mass of this compound which contains 4.92 x 1024 atoms of oxygen?