Chem 1711 Exam 1 September 25, 2014 Dr. Susan E. Bates ID#: 2014171 Name 9:00 OR 10:00 Please do not remove this page. The periodic table, constants, and equations you may need are on the last page of this exam. Feel free to remove it, and use it as scrap paper. All pages must be turned in. Be sure to fill out and bubble in the proper letters and numbers on the ScanTron sheet for the following information: your name Test Form A the 9-digit ID number given above (rightmost digit blank) You should answer questions for Part II (1-14) on the Scantron sheet. You will not have the Scantron returned to you, so if you would like to know what you answered after the exam is returned, circle your answers on this form as well.
Chem 1711: Exam 1 Part I: Short Answer (43 points) Name 1. Provide the missing IUPAC name or chemical formula for each of the following. NH 4 + nickel (III) chlorate SeF 6 zinc hydrogen phosphate H 2 C 2 O 4 cesium oxide 2. Perform the following unit conversion; report your answer with the correct number of significant figures. 0.003265 mol/l = pmol/mm 3 3. a. Give the name of the noble gas in the 3 rd period of the periodic table. b. Give the symbol of one metalloid. c. Consider the element in group IIB of the 4 th period of the periodic table. Which of the following best describes this element? Circle the one best answer below. alkali metal alkaline earth metal transition metal nonmetal main group metal 4. Consider atoms A, B, C, & D, and their numbers of protons, neutrons and electrons: atom p n e A 35 45 35 B 45 57 45 C 25 55 22 D 40 50 40 a. Which one of these {A, B, C, or D} is a cation? b. Which one of these {A, B, C, or D} has a mass number = 90? c. Which one of these {A, B, C, or D} is an atom of rhodium? 5. Consider 2 samples of equal volume. One of these is a sample of silver (mass = 105 g), and the other is a sample of gold (mass = 193 g). Which metal has the greater density? 6. Indicate whether each of the following statements is True or False. a. Consider the calculation 26.924 18.6 =. The answer will have 2 significant figures. b. Rutherford's experiments with alpha rays established that electrons are found in the nucleus of all atoms. c. The exact number 1500 has 4 significant figures. d. The Law of Conservation of Mass says that the total mass remains constant during chemical change. 7. a. Name the following compound: FeSO 4 7H 2 O b. Determine the formula mass (in amu) for this compound. amu
8. A 4.24 g sample of an element contains 2.66 x 10 22 atoms. a. Detemine the molar mass of this element. b. What is the name of this element? 9. a. Balance the following chemical equation: FeS 2 (s) + O 2 (g) Fe 2 O 3 (s) + SO 2 (g) b. Determine the mass (in g) of FeS 2 required to react with excess O 2 to produce 42.00 mol iron (III) oxide. g 10. Consider the following reaction: 2 Al (s) + 6 HCl (aq) 2 AlCl 3 (aq) + 3 H 2 (g). 4.00 mol Al (s) are allowed to react with 10.50 mol HCl (aq). Complete a - d below based on this reaction mixture. a. Complete the reaction table: 2 Al (s) + 6 HCl (aq) 2 AlCl 3 (aq) + 3 H 2 (g) before rxn: 4.00 mol 10.50 mol 0 mol 0 mol change: after rxn: / 43 b. Identify the limiting reactant. c. What is the theoretical yield (in mol) of AlCl 3? d. What amount (in mol) of excess reactant remains unconsumed when the reaction is complete? Part II: Multiple Choice (42 points). For each of the following questions, indicate the one best answer by bubbling in the appropriate letter on the provided Scan Tron answer sheet. 1. Which of the following metals can form more than one cation? i. Rb ii. Cd iii. Sn iv. Fe v. Ga a. all of these b. iii & iv c. i, ii & iv d. ii, iii & iv e. none of these 2. Which one of the following is not an oxoacid? a. acetic acid b. sulfurous acid c. phosphoric acid d. hydrofluoric acid e. hypobromous acid 3. Which one of the following relationships is not true? a. 1 in 2 > 1 cm 2 b. 1 ml > 1 µl c. 0 C = 0 K d. 1 gal > 1 L e. 1 g > 1 amu
4. Which one of the following statements is true? a. For a neutral atom, the number of electrons is equal to the atom's mass number. b. 54 Fe 2+ and 54 Fe 3+ are two isotopes of the same element. c. The formation of a magnesium ion requires the loss of 1 electron from the nucleus. d. The mass of 1 electron is equal to the mass of 1 proton. e. One atom of technetium-93 has a mass of approxiately 93 amu. 5. Calculate the average atomic mass of element X (in amu) using the following data: isotope isotope mass percent abundance 109 X 108.927 amu??? 110 X 110.024 amu 31.12% 112 X 111.956 amu 4.57% a. 109.4 amu b. 110.3 amu c. 148.3 amu d. 111.0 amu e. 108.9 amu 6. Consider the following information about element A. A is malleable and a good conductor of electricity. When A forms a binary compound with chlorine, the chemical formula is ACl 2. Which of the following is most likely the identity of A? a. Rb b. Y c. Zn d. S e. Ag 7. The density of copper is 8.96 g/cm 3. A cube of copper has a mass of 234 g. Determine the length (in cm) of each edge of the cube. a. 26.1 cm b. 6.16 cm c. 8.70 cm d. 12.8 cm e. 2.97 cm 8. The molecular formula of Vitamin C is C 6 H 8 O 6. What is the empirical formula for this compound? a. CHO b. CH 2 O c. C 3 H 4 O 3 d. C 6 H 8 O 6 e. there is not enough information provided to answer 9. Which sample contains the largest number of atoms? a. 1.00 mol CH 4 b. 2.00 mol NH 3 c. 3.00 mol Kr d. 2.00 mol CH 3 Cl e. 1.00 mol HNO 3 10. Determine the mass percent Cl in C 6 H 4 Cl 2. a. 24.1% b. 48.2% c. 2.07% d. 8.29% e. 35.5%
11. 3.00 mol of a molecular substance has a mass of 234.4 g. Determine the mass (in g) of one molecule of this substance. a. 3.89 x 10 22 g b. 1.17 x 10 21 g c. 1.30 x 10 22 g d. 1.27 x 10 2 g e. 7.71 x 10 21 g 12. One formula unit of vanadium (V) sulfite is composed of sulfite ions and oxygen atoms. a. 5 sulfite ions; 15 oxygen atoms b. 1 sulfite ion; 4 oxygen atoms c. 2 sulfite ions; 5 oxygen atoms d. 1 sulfite ion; 3 oxygen atoms e. 5 sulfite ions; 20 oxygen atoms 13. A student in lab analyzes an unknown solution to determine its density. Three 10.00 ml samples were weighed individually, and found to have masses of 10.245 g, 10.281 g, and 10.198 g respectively. The actual density of this student's unknown is 1.017 g/ml. What is his percent error? a. 9% b. 0.7% c. 2% d. 0.4% e. 17% 14. In your "Reactions and Solubility" lab, which one of the following ions was always soluble? a. Na + b. Pb 2+ c. CO 3 2 d. Ag + e. Cr 3+ / 42 Part III (15 points): Problems. Work each of the following problems. Show all work clearly; work with units in all steps; report your answers with correct units and significant figures. No partial credit will be given if I cannot follow your work. 1. A non-si unit of mass used in pharmaceutical work is the grain (gr). One aspirin tablet contains 5.0 gr of aspirin. A 185 lb arthritic person takes 2 aspirin tablets per day. a. Calculate the mass (in mg) of aspirin in 2 tablets. b. Calculate the dosage for this person in mg aspirin/kg body mass. mass = mg dosage = mg/kg c. At this rate of 2 tablets per day, how long (in days) are required for this person to consume 0.500 lb aspirin? days
2. When baking cookies, baking soda, also known as sodium hydrogen carbonate, is added because heating it produces carbon dioxide gas that allows the cookies to rise. This reaction is described by the following equation: 2 NaHCO 3 (s) Na 2 CO 3 (s) + H 2 O (g) + CO 2 (g) molar mass (g/mol): 84.00 106.0 18.02 44.01 Suppose a cookie recipe calls for 1 teaspoon of baking soda (1 teaspoon = 4.00 g baking soda). a. What is the theoretical yield (in g) of CO 2 when 1 teaspoon of baking soda reacts in the process of baking cookies? g b. Upon analysis of the cookie, a chemist found that 2.13 g of sodium carbonate was produced when the baking soda was heated. Determine the actual yield (in g) of CO 2. g c. Determine the percent yield of CO 2. % 3. A sample of a compound commonly referred to as dioxane (which is composed of C, H, and O) was analyzed by combustion analysis. A 3.19 g sample of dioxane was determined to be 9.15% H and 36.32% O by mass. a. Determine the empirical formula of the dioxane. b. If the molar mass of dioxane is 88.11 g/mol, determine the molecular formula of the compound. / 15
Some information that you may find useful: N A = 6.022 x 10 23 mol 1 1 in = 2.54 cm 1 cm 3 = 10 3 L 1 gal = 3.785 L 15 gr = 1.0 g 1 lb = 453.59 g I A II A III B IV B V B VI B VII B VIII I B II B III A IV A V A VI A VII A inert gases 1 H 1.008 2 He 4.003 3 Li 6.941 11 Na 22.98 19 K 39.10 37 Rb 85.46 55 Cs 132.9 87 Fr (223) 4 Be 9.012 12 Mg 24.31 20 Ca 40.08 38 Sr 87.62 56 Ba 137.3 88 Ra 226.0 21 Sc 44.96 39 Y 88.91 57 * La 138.9 89 * Ac (227) 22 Ti 47.90 40 Zr 91.22 72 Hf 178.4 104 Rf (267) 23 V 50.94 41 Nb 92.91 73 Ta 180.9 105 Db (268) 24 Cr 52.00 42 Mo 95.94 74 W 183.8 106 Sg (271) 25 Mn 54.94 43 Tc 98.91 75 Re 186.2 107 Bh (272) 26 Fe 55.85 44 Ru 101.0 76 Os 190.2 108 Hs (270) 27 Co 58.93 45 Rh 102.9 77 Ir 192.2 109 Mt (276) 28 Ni 58.71 46 Pd 106.4 78 Pt 195.0 110 Ds (269) 29 Cu 63.55 47 Ag 107.8 79 Au 196.9 111 Rg (280) 30 Zn 65.37 48 Cd 112.4 80 Hg 200.5 112 Cn (285) 5 B 10.81 13 Al 26.98 31 Ga 69.72 49 In 114.8 81 Tl 204.3 113 Uut (286) 6 C 12.01 14 Si 28.09 32 Ge 72.59 50 Sn 118.6 82 Pb 207.2 114 Fl (289) 7 N 14.01 15 P 30.97 33 As 74.92 51 Sb 121.8 83 Bi 208.9 115 Uup (288) 8 O 16.00 16 S 32.06 34 Se 78.96 52 Te 127.6 84 Po (210) 116 Lv (293) 9 F 19.00 17 Cl 35.45 35 Br 79.90 53 I 126.9 85 At (210) 117 Uus (294) 10 Ne 20.17 18 Ar 39.95 36 Kr 83.80 54 Xe 131.3 86 Rn (222) 118 Uuo (294) 58 Ce 140.1 90 Th 232.0 59 Pr 140.9 91 Pa (231) 60 Nd 144.2 92 U 238.0 61 Pm (147) 93 Np (237) 62 Sm 150.4 94 Pu (242) 63 Eu 151.9 95 Am (243) 64 Gd 157.3 96 Cm (247) 65 Tb 158.9 97 Bk (247) 66 Dy 162.5 98 Cf (251) 67 Ho 164.9 99 Es (254) 68 Er 167.3 100 Fm (253) 69 Tm 168.9 101 Md (256) 70 Yb 173.0 102 No (254) 71 Lu 174.9 103 Lr (262)