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Chemistry I-Honors First Semester Exam Review Packet Solution Set 1. C For a neutral atom of an element to become a cation through a chemical reaction, which of the following must be true? A) the atom must lose protons; B) the atom must gain protons; C) the atom must lose electrons; D) the atom must gain electrons; E) the atom may either lose electrons or gain protons; F) the atom may either gain electrons or lose protons. 2. A Which of the following particles has the greatest mass? A) alpha; B) beta; C) gamma; D) neutron; E) neutrino; F) X rays. 3. D Which of the following nuclides would be predicted to be radioactive? A) Sn-118; B) Ca-40; C) Pb-208; D) Am-244; E) Zn-65 4. A Cathode rays were found to be a stream of what type particle? A) electrons; B) protons; C) positrons; D) alpha particles; 5. A Which of the following has 20 protons and 18 electrons? 2+ 2+ 2A) Ca ; B) Ar ; C) Cl ; D) K ; E) S 6. A A beta particle is essentially: A) an electron; B) a positron; C) a proton; E) cations; F) rays. D) a helium nucleus. Identify the reaction type with the reactions below: A. spontaneous radioactive decay B. transmutation (nuclear disintegration) C. fission D. fusion 7. A At-212 -------> Bi-208 + 8. D Sr-90 + Li-7 ------------> Nb-97 + 9. B Ce-140 + -----------> Ba-138 + D 10. C Nd-140 + ------------> Zn-68 + Ge-76 + 2 n ......................................................................................................................... 11. 51.82% Natural silver consists of two isotopes: Ag-107 has a mass of 106.9041 amu and Ag109 has a mass of 108.9047 amu. The periodic table gives the atomic weight of Ag as 107.868 amu. Find the percent abundance of the lighter isotope of Ag. 107.868 amu = 106.9041 (X) + 108.9047 (1.00 - X) - 1.0367 = - 2.0006 X X = 0.51819 = 51.82% 12. 9.93 L If 3.00 liters of a 6.75 M solution of nitric acid are diluted until the new concentration is only 2.04 M, what will be the final volume of this diluted solution? M1V1 = M2V2 V2 = (6.75 M)(3.00 L) / 2.04 M = 9.926 L ================================================================= Matching: each answer should be used only once 13. G He was given credit for discovering the neutron around 1933. 14. F He determined the ratio of charge-to-mass ratio of electrons with his work with cathode rays in 1897. 15. H His oil-drop experiment enabled scientists to measure the charge on the electron. 16. B He concluded that the atom had a small, compact, positively-charged nucleus surrounded by electrons based on his gold-foil experiment. 17. J He invented the mass spectrograph, an instrument that is able to separate atoms of slightly different masses (isotopes). 18. O This Italian physicist was instrumental in the development of the first atomic bomb. He also prepared more than 40 different radioactive elements through neutron bombardment. 19. L He is credited with the discovery of radioactivity. 20. A Developed the first comprehensive atomic theory based on experimental observations of Proust and Lavoisier. He proposed the Law of Multiple Proportions. 21. D This ancient Greek first proposed idea that matter had small, indivisible particles. ............................................................................. A. Dalton B. Rutherford C. Moseley D. Democritus E. Aristotle F. Thomson G. Chadwick H. Millikan I. Gay-Lussac J. Aston K. Bohr L. Becquerel M. Roentgen N. Goldstein O. Fermi ............................................................................. Answer the following questions based on the -2 anion of an isotopic form of sulfur: S-35 22. 35 What is the A number for this nuclide? 23. 16 What is the Z number for this nuclide? 24. 16 What is the number of protons in the anion form of this nonmetal? 25. 18 What is the number of electrons in the anion form of this nonmetal? 26. 19 What is the number of neutrons in the anion form of this nonmetal? 27. E The element samarium is known to have three isotopes - Sm-148, Sm-149, and Sm-152. The masses of these three isotopes are 148.1010 amu, 149.2005 amu, and 152.4107 amu, respectively. If the lightest isotope is three times as abundant as the heaviest, and the middle isotope is known to be 16.00% abundant, what is the percent abundance of the heaviest isotope? The average atomic mass for samarium is 149.18196 amu. A) 14.35; B) 34.08; C) 28.81; D) 56.02; E) 21.00; F) 63.00 149.18196 = 148.1010 amu (3X) + 149.2005 amu (0.1600) + 152.4107 amu (X) 149.18196 = 444.303 X + 23.87208 + 152.4107 X 125.30988 = 596.7137 X X = 0.21000 = 21.00% Complete the following nuclear reactions: 28. Bk-247 Am-245 ( D , ) __?___ 245 95Am + 1H2 0 -1e 29. Ac-228 ( ? , ) Pa-232 228 89Ac + 2He4 0 0 U-235 ( n , ? ) Pa-236 235 92U 30. 31. + Pu-244 32. 20.1 hr 2.43 hr 0 +1e + + 247 97Bk 232 91Pa 91Pa 236 Cm-248 undergoes spontaneous radioactive decay by alpha emission. What is the resulting nuclide? 248 4 244 96Cm 2He + 94Pu -2 -1 What is the half-life of Fm-255 if its decay rate constant is 3.45 x 10 hr ? 0.693 = (k)(t1/2) => 33. + 0n1 + -2 -1 t1/2 = 0.693 / 3.45 x 10 hr = 20.086 hr How many hours does it take for a 3.000-gram sample of Ho-166 to decay until only 0.375 grams remains behind? The half-life of Ho-166 is 48.6 minutes. 3.000 g 1.500 g 0.750 g 0.375 g or 0.693 = (k)(t1/2) => [3(48.6 min)] / 60 = 2.43 hr k = 0.693 / 48.6 min = 0.01426 min-1 ln(3.000 / 0.375) = (0.01426 min-1) t t = 2.079 / 0.01426 = 145.8 min => / 60 = 2.43 hr 34. 18.2 g How many grams of Co-56 were initially present if only a 3.00-gram sample remains -3 -1 after 205 days? Decay rate constant is known to be 8.79 x 10 days ? -3 -1 ln( X / 3.00 g) = (8.79 x 10 days )(205 days) = 1.802 X / 3.00 = 6.06 => 35. 1.50% X = 18.2 g What percentage of Fr-223 remains behind from a 5.00-mg sample after 2.20 hours if the half-life for Fr-223 is known to be 21.8 minutes? 0.693 = (k)(t1/2) => k = 0.693 / 21.8 min = 0.0318 min-1 ln(100 / X) = (0.0318 min-1)(2.20 hr)(60 min/1 hr) = 4.20 100 / X = 66.4 => X = 1.50% For the following reactions, give the sum total of all coefficients (including the understood 1"s). Be sure to balance the equation by the method indicated. Remember to reduce to lowest terms!!! (red: +3 e-1) x 2 36. +5 2 HNO3 14 + -2 3 H2S 0 +2 3 S + 2 NO ------------> + 4 H2O (oxid: -2 e-1) x 3 Complete the following nuclear reactions. Put the proper item (target, bombarding particle, expelled particle, or product) in the blank to the left. 37. 21 12Mg Al-25 ( , ) ___?___ 25 13Al + 1e0 + 1H2 38. Y-90 ( D , __?__ ) Nb-92 90 39Y 39. Cm-249 ( __?__ , 3 n ) Cf-250 249 96Cm ___?___ ( p , ) Np-238 237 92U 40. 41. 237 92U 158 61Pm 4 2He 0 -1e 21 12Mg + + 92 41Nb + 2He4 3 0n1 + + 1H1 0 0 + 250 98Cf 238 93Np When Er-168 is hit by a beta particle, it undergoes a series of decays. In the process, it gives off 2 alpha particles, a positron and a deuteron as well as a daughter nuclide. What is the identity of this resulting daughter nuclide after this decay process? 68Er 168 + 0 -1e 2 2He4 + +1e 0 + 1H2 + 158 61Pm Change-in-Oxidation Number Method: (red: +2 e-1) x 5 +7 5 KIO4 + +2 2 Mn(NO3)2 + +7 +5 2 HMnO4 + 5 KIO3 + 4 HNO3 3 H2O ----------> (oxid: -5 e-1) x 2 42. Mn+2 ion For the equation above, what was the substance oxidized? 43. Mn+2 ion What was the reducing agent? 44. 10 45. 21 What was the total number of electrons transferred in this redox reaction? What is the sum total of all coefficients when the equation is balanced? (red: +6 e-1) x 1 +12 -2 -2 -2 +1 Cr2O7 + 14 H + 3 S ----------> +6 2(+3) 0 3+ 2 Cr + 3 S + 7 H2O (oxid: -2 e-1) x 3 46. Cr2O7 -2 For the equation above, what was the substance reduced? 47. 2 How many electrons were lost through oxidation before the equation was balanced? 48. 6 What was the total number of electrons transferred in this redox reaction? 49. 30 What is the sum total of all coefficients when the equation is balanced? Half-cell Method: 3 Ag2S + 8 HNO3 6 AgNO3 50. Write the balanced oxidation half-reaction. 51. Write the balanced reduction half-reaction. 52. 26 + 2 NO + 3S + 4 H2O ( S-2 S + 2 e-1 ) x 3 ( 3e-1 + 4 H+1 + NO3-1 NO + 2 H2O ) x 2 What is the sum total of all coefficients when the equation is balanced? 3 Cl2 + 6 KOH 5 KCl + 1 KClO3 + 3 H2O 53. Write the balanced oxidation half-reaction. ( 6 OH-1 + Cl ClO3-1 + 3 H2O + 5 e-1 ) x 1 54. Write the balanced reduction half-reaction. (1 e-1 + Cl Cl-1 ) x 5 55. 18 What is the sum total of all coefficients when the equation is balanced? Balance the remaining equations by your method of choice: Give the sum total of all coefficients in the blank. Don't forget the understood "1". 56. 33 57. 75 2 PbCrO4 + 16 HCl 2 C10H22 + 31 O2 2 PbCl2 + 2 CrCl3 + 3 Cl2 + 8 H2O 20 CO2 + 22 H2O 58. 26 2 KMnO4 + 5 H2S + 3 H2SO4 5 S + 2 MnSO4 + 1 K2SO4 + 8 H2O 59. 9 3 PCl5 + 1 P2O5 5 POCl3 60. Ba3P2O8 or What is the empirical formula of a substance that is analyzed and found to better as Ba3(PO4)2 contain 68.43% barium, 10.30% phosphorus, and 21.27% oxygen? Ba 68.43 g -------137.3 g/mol = 0.498 mol P 10.30 g ------31.0 g/mol = 0.332 mol O 21.27 g --------16.0 g/mol = 1.33 mol divide all three by 0.332 mole => Ba : P : O = (1.5 : 1 : 4 ) x 2 Ba3P2O8 or better as Ba3(PO4)2 61. N4O8 4.72 grams of a gas at STP conditions occupies 575 ml. This gas is known to contain 30.435% nitrogen and 69.565% oxygen. What is the true, or molecular formula? 30.435 g N / 14.0 g/mol = 2.17 mol 69.565 g O / 16.0 g/mol = 4.35 mol 4.72 g 22.4 L ---------- x ----------0.575 L 1 mole = 184 g/mol => NO2 M.Wt. 46.0 g/mol 184 / 46 = 4 (NO2)4 = N4O8 62. 113 g How many grams of barium hydroxide need to be added to 750.0 ml of water in order to produce a 0.880 M solution of this base? 0.7500 L 63. C20H27O6 0.880 mol cpd 171.3 g cpd x ------------------- x ----------------1 L soln. 1 mol cpd = 113.058 g An organic compound is known to contain 48.00 grams of carbon, 1.20 moles of 24 oxygen atoms, and 3.25 x 10 atoms of hydrogen. If the molecular weight of this compound is known to be 363 grams/mole, what its true molecular formula? 48.00 g C / 12.0 g / mol = 4.00 mol C 3.25 x 1024 atom H / Av# = 5.40 mol H 1.20 mol O C: H:O = (3.33 : 4.50 : 1.0) x 6 C20H27O6 Since the M.Wt of C20H27O6 = 363, then the empirical formula is the true, or molecular formula. 64. 0.441 M What is the molarity of a solution if 1.35 grams of sodium perchlorate is added to enough water to make 25.0 ml of solution? NaClO4 M.Wt. = 122.5 g/mol 1.35 g cpd / (122.5 g/mol) / 0.0250 L = 0.441 M 65. T - 66. B F For matter to be classified as heterogeneous, it must be composed of more than one phase, or state, of matter. Two different solids can be mixed together and be heterogeneous. What is the basic structural unit of covalent compounds? A) atom; B) molecule; C) isotope; D) nuclide; E) quark; F) element; G) cation & anion. 67. F What is the term that describes a homogeneous substance composed of only one type of atom? A) alloy; B) molecule; C) isotope; D) nuclide; E) quark; F) element; G) compound 68. D Distillation is used to separate substances in the same solution having different: A) freezing points; B) solubilities; C) densities; D) boiling points; E) none of these. 69. B Salt is dissolved in water. The water is called the: A) solution; B) solvent; C) solute; D) interface. Match the Latin name for each of the following elements using the following key: A. stannum B. plumbum C. aurum D. stibium E. kalium F. hydragyrum G. cuprum H. fermium I natrium J. ferrum 70. B lead 71. I sodium 72. D antimony 73. J iron Classify the following materials using the following key: (A) heterogeneous mixtures , (B) elements , (C) compounds , (D) true solutions 74. A mayonnaise 75. D 3% hydrogen peroxide 76. D pewter 77. B samarium 78. C sodium carbonate 79. A soured (curdled) milk 80. D fog ================================================================== 81. B What group of elements is being described: generally low melting and boiling points; high electronegativities; high ionization potentials; poor electrical conductors at room temperature. A) metals; B) nonmetals; C) metalloids; D) inert (noble) gases 82. B What phase (state) of matter is being described: moderate rate of diffusion; have definite volume; no definite shape; moderate kinetic energy [K.E. is approximately equal to the IMF (intermolecular forces)] A) solid; B) liquid; C) gas; D) plasma 83. A What is the most abundant element in the universe? A) H; B) He; C) O; D) Ar; E) Si; F) C; G) Al; H) Fe 84. E What is the second most abundant element in the biosphere (crust, atmosphere & oceans)? A) H; B) He; C) O; D) Ar; E) Si; F) C; G) Al; H) Fe 85. D What is the most abundant noble gas in the earth's atmosphere? A) H; B) He; C) O; D) Ar; E) Si; F) C; G) Al; H) 86. H Which of the following elements is a member of the alkaline earth family? A) H; B) He; C) O; D) Ar; E) Si; F) C; G) Al; H) Ba 87. E Which of the following elements is a metalloid? A) H; B) He; C) O; D) Ar; E) Si; 88. amphoteric 89. ductility 90. colloids F) C; G) Al; H) Fe What is the term for a substance that can act as either an acid or a base? An example would be NaHCO3. What is the term that is used to describe a metal's ability to be drawn into a wire? The Tyndall effect is a characteristic of what classification of matter? What is the term for the following chemical, physical or nuclear changes? 91. nuclear fission A nuclide is bombarded with a subatomic particle such as a neutron, causing the nuclide to fragment into two similarly-sized lighter nuclides. 92. reduction gain of electrons; for example, Fe +3 - o + 3 e -----> Fe 93. metathesis or double replacement exchange of anions and cations between two compounds; for example, AgNO3(aq) + KI(aq) -----> KNO(aq) + AgI(s) 94. condensation Rainfall is an example of this physical change. 95. vulcanization Addition of sulfur to rubber produces a more durable, and much stiffer substance through this chemical process. 96. neutralization Reaction of an acid with a base to produce water as well as a byproduct salt. 97. photosynthesis Energy-absorbing chemical process in which carbon dioxide gas and water are converted into glucose and oxygen gas, through a series of complex reactions. 98. 5.66 x 10-23 g What is the mass, in grams, of a single molecule of hydrosulfuric acid? (34.1 g/mol )( 1 mol / Av #) = 5.66 x 10-23 g 107 g O 99. A 30.0-liter sample of dinitrogen pentoxide contains how many grams of oxygen? 30.0 L 100. 5.09 x 1020 1 mol cpd 5 mol O 16.0 g O x ------------- x ------------ x ------------ = 22.4 L cpd 1 mol cpd 1 mol O 107.14 g oxygen How many molecules of water are present in 80.0 milligrams of ferric chlorate tetrahydrate? 0.0800 g 1 mol cpd 4 mol H2O Av. # H2O x --------------- x ------------ x ------------ = 378.3 g cpd 1 mol cpd 1 mol H2O 101. 68.30% 5.09 x 1020 H2O molecules What is the percentage of metal in a 2.000-gram sample of barium dichromate? BaCr2O7 % metal = [137.3 + 2(52.0)] / [137.3 + 2(52.0) + 7(16.0)] x 100 = 68.298 % 102. 16.9 g CO What is the mass of exactly 13.50 liters of carbon monoxide gas at STP conditions? 13.50 L CO 1 mol CO 28.0 g CO x ------------- x --------------- = 22.4 L CO 1 mol CO 16.875 g CO 103. 6.39 x 1023 H atoms What is the number of hydrogen atoms in 34.7 grams of phosphoric acid? 34.7 g A 104. 13.5 moles O2 1 mol A 3 mol H Av. # H x ---------- x ------------ x ------------ = 98.0 g A 1 mol A 1 mol H 6.39 x 1023 H atoms If you had 3.00 moles of auric carbonate, how many moles of pure oxygen gas could you get from this sample? [Hint: remember that oxygen gas is diatomic!] Au2(CO3)3 3.00 mol cpd 105. 3.890 x 1019 9 mols O x -----------1 mol cpd 1 mol O2 x ------------ = 2 mols O 13.5 mols O2 How many total atoms are in exactly 1.000 milligram of sodium tetraborate? Na2B4O7 0.001000 g 106. 0.446 mol 1 mol cpd 13 mol atoms Av. # atoms x --------------- x ------------ x ------------ = 201.2 g cpd 1 mol cpd 1 mol atoms atoms How many moles of sulfuric acid do you need in order to release 10.0 liters of hydrogen gas (H2) at STP? 10.0 L H2 107. 2.77 x 1023 3.8896 x 1019 1 mol H2 1 mol acid x ------------- x --------------- = 22.4 L H2 1 mol H2 0.4464 mol acid If a compound of stannic chloride contains 45.53% tin by weight, how many chloride ions are there in 30.0 grams of this compound? SnCl4 30.0 g or 30.0 g 54.47 g Cl 1 mol Cl Av. # Cl x --------------- x ------------ x ------------ = 100.0 g cpd 35.5 g Cl 1 mol Cl 2.77 x 1023 1 mol cpd 4 mol Cl Av. # Cl x --------------- x ------------ x ------------ = 260.7 g cpd 1 mol cpd 1 mol Cl 2.77 x 1023 atoms of Cl atoms of Cl 108. 7.53 x 1022 How many ions (total of both cations and anions) are there in 0.0250 moles of chromium(III) oxalate? Cr2(C2O4)3 0.0250 mol cpd 109. 1.01 mol 5 mols ions Av. # ions x --------------- x ---------------- = 1 mol cpd 1 mol ions 7.53 x 1022 total ions How many moles of metal can be recovered from 125 grams of strontium molybdate? SrMoO4 125 g cpd 1 mol cpd 2 mol Sr & Mo x --------------- x ------------------- = 247.5 g cpd 1 mol cpd 1.01 mol Give the correct name for the following compounds (spelling must be completely correct): 110. SrF2 strontium fluoride 111. H2S(aq) hydrosulfuric acid 112. P2Br5 diphosphorus pentabromide 113. Ag2S2O3 silver thiosulfate 114. FeCO3 (common name) ferrous carbonate 115. Sn(HSO3)2 (common name) stannous bisulfite 116. ZrBa(PO4)2 zirconium barium phosphate 117. NH4C2H3O2 ammonium acetate 118. HNO3(aq) nitric acid 119. Co2(C2O4)3 cobalt(III) oxalate 120. K2MnO4 potassium manganate 121. H3BO3(aq) boric acid 122. MnSO4 . 6 H2O manganese(II) sulfate hexahydrate 123. Cu(SCN)2 (common name) cupric thiocyanide 124. CdHPO4 cadmium monohydrogen phosphate 125. HCHO2(aq) formic acid 126. NaBrO sodium hypobromite 127. K2O2 potassium peroxide 128. Mg(CN)2 magnesium cyanide 129. (NH4)2B4O7 ammonium tetraborate For the following compounds, give the proper formula (it must be completely correct): 130. scandium oxide Sc2O3 131. acetic acid HC2H3O2(aq) 132. trinitrogen heptaselenide N3Se7 133. carbonic acid H2CO3(aq) 134. hydrofluoric acid HF(aq) 135. chromium (III) chromate Cr2(CrO4)3 136. mercuric hydroxide Hg(OH)2 137. auric phosphide AuP 138. beryllium bisulfide Be(HS)2 139. cesium monohydrogen phosphate Cs2HPO4 140. xenon hexafluoride XeF6 141. cobaltous chloride tetrahydrate CoCl2 . 4 H2O 142. nickel (II) permanganate Ni(MnO4)2 143. calcium oxalate CaC2O4 144. lithium telluride Li2Te 145. aluminum nitrite Al(NO2)3 146. rubidium hypochlorite RbClO 147. plumbic ferrocyanide Pb[Fe(CN)6] 148. barium molybdate nonahydrate BaMoO4 . 9 H2O 149. sulfuric acid H2SO4(aq) For the following equations (A) indicate the type of reaction (SYN, DEC, SR, or DR); (B) indicate whether the reaction will go as written; (C) if the reaction will not go as written, clearly indicate what is wrong with the equation. 150. DR SrCO3(aq) + 2 HCl(aq) -------------> H2O(liq) + CO2(g) + SrCl2(aq) YES 151. 152. 153. 154. DEC 2 CuO(s) ---------------> NO Oxides of copper are stable and do not decompose with heat. SR Pt(s) + H2SO4(aq) --------------> NO Platinum is less active than hydrogen. SYN K2O(s) + CO2(g) -----------> K2CO3(s) YES (example of a basic anhydride and an acidic anhydride combining) DR Na2S(aq) + Cu(NO3)2(aq) 2 Cu(s) + O2(g) PtSO4(s) + H2(g) -----------> CuS(s) + 2 NaNO3(aq) YES 155. SR YES Ca(s) + 2 H2O(g) (steam) --------------> Ca(OH)2(aq) + H2(g) 156. SYN Cu(s) + S(s) ------------> CuS(s) YES 157. DEC 2 Co(OH)3(s) -------------> Co2O3(s) + 3 H2O(liq) YES 158. DR Pb(NO3)2(aq) + 2 KI(aq) ----------> 2 KNO3(aq) + PbI2(s) YES 159. 160. SR Sn(s) + ZnCl2(aq) -----------> Zn(s) + SnCl2(aq) NO Tin is less active than zinc. DEC LiF(s) --------D.C.---------> 2 Li(s) + F2(g) YES 161. 162. DR FeS(s) + NO FeS is not soluble, so the ions are not free to interact. DEC NO 163. DEC BaCl2(aq) ------------> BaS(s) + FeCl2(aq) CaSO4(s) ---------------> CaO(s) + SO3(g) II-A sulfates are too stable and do not decompose with heating. 2 Mg(NO3)2(s) ---------------> 2 MgO(s) + 4 NO2(g) + O2(g) YES 164. SR NO 165. SYN NO Br2(liq) + 2 KCl(aq) -------------> 2 KBr(aq) + Cl2(g) Bromine is less active than chlorine. 2 SO3(g) + 6 H2O(liq) -------------> 2 S(OH)2(aq) - wrong product - should produce an acid since SO3 is an acidic anhydride Complete the following reactions: 166. calcium carbonate plus potassium hydroxide NR 167. diphosphorus pentoxide plus water H3PO4 168. cadmium hydroxide plus hydrosulfuric acid CdS(ppt) + H2 O 169. nitrogen gas and hydrogen gas are mixed together, and heated, with a catalyst present NH3 170. 5.43 x 1014 sec-1 What is the frequency of green light with a wavelength of 552 nm? c = => = (3.00 x 1017 nm/sec) / 552 nm = 5.43 x 1014 sec-1 171. 1.59 x 10-16 J What is the energy of a photon from the X-ray region of the spectrum if its wavelength is 12.5 Angstroms? E = hc / = [(6.626 x 10-34 J-sec)(3.00 x 1018A/sec)] / 12.5 A = 1.59 x 10-16 J 172. -8.72 x 10-20 J What is the energy associated with an electron in the fifth ground state shell? En = -RH(1/n2) = -2.18 x 10-18 J (1 / 25) = -8.72 x 10-20 J 173. 2.18 x 10-18 J How much energy must be provided in order to completely ionize one electron from the ground state of a hydrogen atom? E = RH(1/n2initial - 1/n2final) = 2.18 x 10-18 J (1 / 1 - 1/ ) = 2.18 x 10-18 J A student dissolves 3.00 grams of solid copper metal in an excess of 15.0 M nitric acid, producing nitric oxide (NO), cupric nitrate, and water. Once the gas was given off, the blue solution was heated to drive off all of the water and 4.00 grams of a blue precipitate were recovered. The reaction was conducted at STP conditions. Answer the following questions based on this information. 174. Write the balanced equation for this reaction. [Hint: the sum total of all coefficients adds up to 20.] 3 Cu + 8 HNO3(aq) 175. 0.7055 L 1.13 g 0.126 mol 8.86 g 45.1% 1 mol Cu 2 mol NO 22.4 L NO x ------------- x -------------- x -------------63.5 g Cu 3 mol Cu 1 mol NO = 0.7055 L 1 mol Cu 4 mol H2O 18.0 g H2O x ------------- x -------------- x -------------- = 1.1338 g 63.5 g Cu 3 mol Cu 1 mol H2O 1 mol Cu 8 mol HNO3 x ------------- x --------------63.5 g Cu 3 mol Cu = 0.12598 mol How many grams of cupric nitrate should have been produced, assuming 100% yield? 3.00 g Cu 179. 4 H2 O How many moles of nitric acid were needed initially? 3.00 g Cu 178. 3 Cu(NO3)2 + What is the mass of water produced? 3.00 g Cu 177. 2 NO + How many liters of nitric oxide should have been formed? 3.00 g Cu 176. 1 mol Cu 3 mol Cu(NO3)2 187.5 g cpd x ------------ x ------------------ x -------------- = 8.858 g cpd 63.5 g Cu 3 mol Cu 1 mol cpd What is the percent yield for this reaction? (4.00 / 8.86) x 100 = 45.146 % 180. 8.4 mL If the student wanted to add exactly the stoichiometric amount of acid needed to dissolve the copper metal, given that the concentration of the acid was 15.0 M, what volume (in ml) of acid would have been needed? (0.126 mol acid )( 1 L / 15.0 mol ) = 0.0084 L = 8.4 mL ===================================================================== -19 181. 6 An outer-shell electron from a lithium atom releases 4.844 x 10 joules of energy as it drops from an excited state back down to its ground state. From what excited state did it originate? E = 4.844 x 10-19 J = -2.18 x 10-18 J ( 1 / n2 - ¼) ( 1 / n2 - ¼) = -0.222 => 1/n2 = 0.0278 n2 = 35.97 n=6 II. 182. When 120.0 ml of a 3.00 M solution of nickel (II) chlorate are mixed with 150.0 ml of a 2.00 M solution of sodium phosphate, 45.0 grams of a bright green precipitate were recovered. Answer the following questions based on this information. Write the balanced equation for this reaction. 3 Ni(ClO3)2(aq) + 2 Na3PO4(aq) 183. 6 NaClO3(aq) + Ni3(PO4)2(ppt) How many moles of each reactant were there? (0.1200 L)(3.00 M) = 0.360 moles Ni(ClO3)2 (0.1500 L)(2.00 M) = 0.300 moles Na3PO4 184. What is the limiting reagent? 0.300 moles Na3PO4 (3 moles Ni(ClO3)2 / 2 moles Na3PO4) = 0.450 mol Ni+2 needed since there are only 0.360 moles of nickel, it is the L.R. 185. How many moles of excess reagent were left unreacted? (0.360 mol LR )( 2 mol ER / 3 mol LR) = 0.240 mol ER used 0.300 mol ER - 0.240 mol = 0.060 moles excess Ni3(PO4)2(ppt) 186. What is the precipitate? 187. How many grams of precipitate should have been formed theoretically? 0.360 mol LR 188. 1 mol ppt 366.1 g ppt x ------------- x --------------3 mol LR 1 mol cpd = 43.9 g ppt What is the percent yield for this reaction? [Be careful!] (45.0 g / 43.9 g) x 100 = 102% 189. +2 What is the [Ni ] in the final solution? none - it was the precipitating ion & the LR -3 0.060 mol / 0.270 L = 0.222 M 190. What is the [PO4 ] in the final solution? 191. What is the [ClO3 ] in the final solution? 192. What is the [Na ] in the final solution? 193. How many more moles of the limiting reagent would need to be added to produce stoichiometric amounts? - + (0.360 mol) x 2 / 0.270 L = 2.67 M (0.300 mol) x 3 / 0.270 L = 3.33 0.450 mol - 0.360 mol = 0.090 mol M Consider the following set of elements in answering set of questions: Mn, V, He, Ar, Ba, Co, Pm, P, Br, Pt, Se There may be more than one element used to correctly answer the questions. 194. He Which of the elements has the highest first ionization potentials? 195. He, Ar, Ba Which of the following has a negative electron affinity? 196. Pt Which of the following has an electron with the following quantum numbers: n = 5 l = 2 ml = -1 s = -1/2 5d1 197. Ba Which of the following has the lowest electronegativity value (is the most electropositive element)? 198. Pt Which has the greatest density? 199. He, Ar, Ba Which shows diamagnetism? 200. Mn, V, Co, Pt Which forms colored salts in its cationic form? 201. Ba Which exhibits the largest atomic radius? 202. P, Br, Se Which exhibits a stable ionic form that is larger in size than its neutral atomic size? 203. P Which shows a higher-than-normal ionization energy due to its half-filled subshell stability? 204. Se Which is classified as a chalcogen? 205. Pm Which is classified as a rare-earth metal? 206. Br Which is classified as a halogen? 207. Ba An oxide of which of the following would exhibit the strongest basic qualities? 208. Br Which tends to be in a stable liquid form at room temperature? 209. [Xe] 6s2 4f14 5d10 6p3 210. Sn What +4 cation has the following configuration: [Kr]4d [ means it lost the 5s2 and 5p2 e-1] 211. P-3 What -3 anion is isoelectronic to a neutral argon atom? Give the electron configuration (using the noble gas core configuration) for a neutral bismuth atom. 10 212. 213. “s” An electron has a magnetic quantum number of +1. It could not be found in which type of subshell? 11.0 m Citizens' band radio operates at a frequency of 27.3 MHz. What is the wavelength of this radiowave? Be sure to include the appropriate unit. c = = 3.00 x 108 m/sec / 27.3 x 106 sec-1 = 10.989 m 214. carmine The distinctive color for the flame test of lithium comes from the fact that each photon -19 has an energy of 2.95 x 10 Joules. What is the color for lithium in its flame test? 2.95 x 10 -19 Joules = DE = hc/ = (6.626 x 10-34 J-sec)(3.00 x 1017 nm/sec) / = 674 nm = red light [Should also know this color from your flame test lab!] 215. Consider the neutral platinum atom and the following sets of quantum numbers. Explain which are valid and which are not. For those that are not valid, explain why they are not valid. n A. 6 m l 0 0 s -1/2 1 YES - valid choice (6s ) B. 4 1 n D. 5 m l 3 -2 +1/2 0 +1/2 NO - not there yet -2 -1/2 E. 5 2 8 NO - “m” value is not possible YES - valid choice (5d ) C. F. 3 3 -3 +1/2 NO - no such thing as a “3f” subshell 216. 4.10 x 105 pm s 2 1 -1 -1/2 1 YES - valid choice (2p ) The Balmer series of emission lines from atomic hydrogen end in the n = 2 energy level. Calculate the wavelength, in picometers, the wavelength of a photon that drops from the sixth shell back to the second shell? E = -2.18 x 10-18 J ( 1 / 36 - 1 / 4) = hc/ = 4.10 x 105 pm 217. Cs < Hf < Ga < Bi < C < Xe Arrange the following elements from smallest to largest first ionization energy: Hf; Bi; C; Xe; Cs; Ga 218. 2 219. 10 How many electrons are needed to fill any one of the orbitals in the 4f subshell? How many electrons are in an atom if the “L” shell has just been filled? 1s2 2s2 2p6 220. Au What is the symbol for the element that is the third best electrical conductor? 221. Ca What is the symbol for the fourth period alkaline earth metal? 222. C What element has the highest melting point? 223. W What metal has the highest melting point? 224. Ar < Al < Bi < Hg < Ca < Cs Arrange the following elements from smallest to largest atomic size: Hg; Bi; Cs; Ar; Ca; Al 224. Ca+2 < Ar < Ba+2 < Cs+1 < S-2 < Te-2 Arrange the following species from smallest to largest size: Ba+2 ; S-2; Cs+1; Ar; Ca+2; Te-2