1CHEM 107 (Spring-2005) Exam 1 (100 pts) Name: ------------------------------------------------------------------------, Clid # ------------------------------- LAST NAME, First (Circle the alphabet segment of your LAST NAME): A-C D-H I-L M-O P-Z Please answer the following questions: Part I: Multiple Choices (48 pts: 12 @ 4 pts each + 4 pts bonus). Circle the ONE best answer: 1. Perform the indicated operations and give the answer in cm with the proper number of significant figures. (12.64 cm – 48 mm + 0.246 m)/(5 cm) = ? a) 6.488 b) 7 c) 6.48 d) 7.4 2. Two atoms are 1.54 x 10-8 cm apart. Express this distance in pm. a) 1.54 x 104 b) 154 c) 1.54 x 10-4 d) 1.54 x 10-2 3. Which of the following does not represent a chemical property? a) rusting iron in air b) stability of gold in air c) density of a substance d) digestion of food 4. The mass of 236 mL of the liquid ethanol is found to be 186 g. What is the density of ethanol in g/mL? a) 1.27 b) 43.9 c) 0.788 d) 1.00 5. Wherever it is found, water is always found to contain oxygen and hydrogen in the mass ratio of 8 to 1. Taken by itself, this fact demonstrates what natural law? a) Conservation of Mass b) Multiple Proportions c) Periodicity d) Constant Composition 6. All of the following statements are correct except a) a proton carries a +1 charge and an electron carries -1 charge. b) a neutron is an uncharged particle with a mass slightly greater than a proton. c) more than 99.9% of an atom’s mass is concentrated in the nucleus. d) the protons and electrons are found in the nucleus of the atom.27. How many electrons, protons, and neutrons are found in a 57Co3+ ion? a) 27 electrons, 27 protons, 30 neutrons b) 30 electrons, 30 protons, 30 neutrons c) 24 electrons, 27 protons, 30 neutrons d) 24 electrons, 30 protons, 30 neutrons 8. Predict the product of the reaction of strontium, Sr with selenium, Se. a) Sr2Se3 b) Sr3Se2 c) SrSe d) Sr2Se2 9. Calculate the number of atoms in 10.0 g He (atomic mass = 4.00 amu)? a) 3.83 x 1018 b) 2.41 x 1023 c) 1.51 x 1024 d) 2.41 x 1024 10. Calculate the percent of chlorine by mass in PCl3. a) 77.5 b) 22.5 c) 50.0 d) 53.4 11. What is the number of moles of Br2 that contain 6.022 x 1021 molecules of Br2? a) 0.01 b) 3.768 x 1019 c) 1.598 d) no answer was given 12. What mass of ammonia, in grams that can be made from 250. g N2(g)? N2 (g) + 3 H2 (g) 2 NH3 (g) a) 304 b) 455 c) 152 d) 500. 13. (Bonus: 4 pts) When 0.225 mol butane, C4H10, is burned with excess oxygen how many moles of oxygen are consumed? 2 C4H10 (g) + 13 O2 (g) 2 CO2 (g) + 10 H2O (l) a) 1.46 b) 0.225 c) 0.900 d) 13.03Part II. Names, formulas and properties (28 pts: 14 @ 2 pts each) – NO Partial Credits 1. (16 pts) Complete the following table with the formula or the name of the compound Name Formula Cobalt(III) sulfate Potassium phosphate Cadmium phosphide Nitric acid FeF3 P2S5 Mg3(PO4)2 HBr (aq) 2. (12 pts) Consider the following substances: SO3, XeF4, F2, CrCl3, GeCl4, NaClO3 and NO2: a) Which are diatomic? ------------------------------------ b) Which are ionic? ------------------------------------ c) Which are molecular (covalent)? ------------------------------------ d) Which compound is derived from a noble gas? ------------------------------------ e) Which compound is derived from a transition metal? ------------------------------------ f) Which compound is derived from a metalloid element? ------------------------------------- Part III. Calculations (24 pts): Show all work for full credit. Please express all answers with the proper units and correct number of significant figures. 1. (8 pts) Naturally occurring silver (Ag) is composed of two isotopes. One of the isotopes has an atomic mass of 106.9051 amu and 51.84% abundance. What is the atomic mass of the other isotope and what is its mass number? Atomic mass: 104.6 Mass number: 10542. (16 pts) Dimethylhydrazine, the fuel used in the Apollo lunar descent module, has a molar mass of 60.10 g/mol. It is made of carbon, hydrogen and nitrogen atoms. The combustion of 2.859 g of the fuel in excess oxygen yields 4.190 g of CO2 and 3.428 g of H2O.Calculate: a) the simplest formula and b) the molecular formula of dimethylhydrazine a) Simplest formula b) Molecular formula5 Exam 1 – Spring 2005 You will have 50 minutes to complete this exam. The exam has 4 pages plus the Periodic Table Reference page. When you are told to do so, tear off the Periodic Table cover sheet and use as required during the exam. 1. 1 1 H 1.01 Periodic Table of the Elements 2 He 4.00 2 3 Li 6.94 4 Be 9.01 5 B 10.816 C 12.01 7 N 14.01 8 O 16.009 F 19.0010 Ne 20.18 3 11 Na 22.99 12 Mg 24.30 13 Al 26.9814 Si 28.08 15 P 30.97 16 S 32.0617 Cl 35.4518 Ar 39.95 4 19 K 39.1 20 Ca 40.08 21 Sc 44.96 22 Ti 47.8823 V 50.94 24 Cr 52.00 25 Mn54.9426 Fe 55.8527 Co 58.9328 Ni 58.6929 Cu 63.5530 Zn 65.3831 Ga 69.7232 Ge 72.59 33 As 74.92 34 Se 78.9635 Br 79.9036 Kr 83.80 5 37 Rb 85.47 38 Sr 87.62 39 Y 88.91 40 Zr 91.2241 Nb 92.91 42 Mo 95.94 43 Tc (98) 44 Ru 101.145 Rh 102.946 Pd 106.447 Ag 107.948 Cd 112.449 In 114.850 Sn 118.7 51 Sb 121.8 52 Te 127.653 I 126.954 Xe 131.1 6 55 Cs 132.9 56 Ba 137.3 57 La 138.9 72 Hf 178.573 Ta 181.0 74 W 183.8 75 Re 186.276 Os 190.277 Ir 192.278 Pt 195.179 Au 197.080 Hg 200.681 Tl 204.482 Pb 207.2 83 Bi 209.0 84 Po (209) 85 At (210) 86 Rn (222) 7 87 Fr (223) 88 Ra 226.0 89 Ac 227.0 104 Rf (261) 105 Db (262) 106 Sg (263) 107 Bh (262) 108 Hs (265) 109 Mt (266) 110 Uun(269) 111 Uuu(272) 112 Uub(277) 58 Ce 140.159 Pr 140.9 60 Nd 144.2 61 Pm(145) 62 Sm 150.463 Eu 152.064 Gd 157.265 Tb 158.966 Dy 162.567 Ho 164.968 Er 167.3 69 Tm 168.9 70 Yb 173.071 Lu 175.0 90 Th 232.091 Pa 231.0 92 U 238.0 93 Np 237.094 Pu (244) 95 Am(243) 96 Cm(247) 97 Bk (247) 98 Cf (251) 99 Es (252) 100 Fm (257) 101 Md (258) 102 No (259) 103 Lr (260) PREFERENCE SHEET FOR CHEM 107 Useful Information: T (˚F) = 1.8 T (˚C) + 32˚ d = m / V Avogadro’s Number, NA =