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; E) cations; F) g rays.
5. A Which of the following has 20 protons and 18 electrons?
A) Ca2+; B) Ar2-; C) Cl-; D) K+; E) S2-
6. A A beta particle is essentially:
A) an electron; B) a positron; C) a proton; 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 + a
8. D Sr-90 + Li-7 ------> Nb-97 + g
9. B Ce-140 + b ------> Ba-138 + D
10. C Nd-140 + a ------> Zn-68 + Ge-76 + 2 n
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11. 51.82% Natural silver consists of two isotopes: Ag-107 has a mass of 106.9041 amu and Ag-109 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
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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.
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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 , b ) __?___ 95Am245 + 1H2 à -1e0 + 97Bk247
29. a Ac-228 ( ? , g ) Pa-232 89Ac228 + 2He4 à 0g0 + 91Pa232
30. b+ U-235 ( n , ? ) Pa-236 92U235 + 0n1 à +1e0 + 91Pa236
31. Pu-244 Cm-248 undergoes spontaneous radioactive decay by alpha emission. What is the resulting nuclide?
96Cm248 à 2He4 + 94Pu244
32. 20.1 hr What is the half-life of Fm-255 if its decay rate constant is 3.45 x 10-2 hr-1?
0.693 = (k)(t1/2) => t1/2 = 0.693 / 3.45 x 10-2 hr-1 = 20.086 hr
33. 2.43 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 à 1.500 g à 0.750 g à 0.375 g [3(48.6 min)] / 60 = 2.43 hr
or 0.693 = (k)(t1/2) => 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 after 205 days? Decay rate constant is known to be 8.79 x 10-3 days-1?
ln( X / 3.00 g) = (8.79 x 10-3 days-1)(205 days) = 1.802
X / 3.00 = 6.06 => X = 18.2 g
35. 1.50% 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
+5 -2 0 +2
36. 14 2 HNO3 + 3 H2S ------> 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. 12Mg21 Al-25 ( b+ , a ) ___?___ 13Al25 + 1e0 à 2He4 + 12Mg21
38. b Y-90 ( D , __?__ ) Nb-92 39Y90 + 1H2 à -1e0 + 41Nb92
39. a Cm-249 ( __?__ , 3 n ) Cf-250 96Cm249 + 2He4 à 3 0n1 + 98Cf250
40. 92U237 ___?___ ( p , g ) Np-238 92U237 + 1H1 à 0g0 + 93Np238
41. 61Pm158 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?
68Er168 + -1e0 à 2 2He4 + +1e0 + 1H2 + 61Pm158
Change-in-Oxidation Number Method:
(red: +2 e-1) x 5
+7 +2 +7 +5
5 KIO4 + 2 Mn(NO3)2 + 3 H2O ------> 2 HMnO4 + 5 KIO3 + 4 HNO3
(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 What was the total number of electrons transferred in this redox reaction?
45. 21 What is the sum total of all coefficients when the equation is balanced?
(red: +6 e-1) x 1
+6
+12 -2 2(+3) 0
Cr2O7-2 + 14 H+1 + 3 S-2 ------> 2 Cr3+ + 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 à 6 AgNO3 + 2 NO + 3 S + 4 H2O
50. Write the balanced oxidation half-reaction. ( S-2 à S + 2 e-1 ) x 3
51. Write the balanced reduction half-reaction. ( 3e-1 + 4 H+1 + NO3-1 à NO + 2 H2O ) x 2
52. 26 What is the sum total of all coefficients when the equation is balanced?
3 Cl2 + 6 KOH à 5 KCl + 1 KClO3 + 3 H2O
53. Write the balanced oxidation half-reaction. ( 6 OH-1 + Cl à ClO3-1 + 3 H2O + 5 e-1 ) x 1
54. Write the balanced reduction half-reaction. (1 e-1 + Cl à 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 2 PbCrO4 + 16 HCl à 2 PbCl2 + 2 CrCl3 + 3 Cl2 + 8 H2O
57. 75 2 C10H22 + 31 O2 à 20 CO2 + 22 H2O
58. 26 2 KMnO4 + 5 H2S + 3 H2SO4 à 5 S + 2 MnSO4 + 1 K2SO4 + 8 H2O
59. 9 3 PCl5 + 1 P2O5 à 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 P 10.30 g O 21.27 g
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137.3 g/mol 31.0 g/mol 16.0 g/mol
= 0.498 mol = 0.332 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 => NO2 M.Wt. 46.0 g/mol
69.565 g O / 16.0 g/mol = 4.35 mol
4.72 g 22.4 L
------x ------= 184 g/mol 184 / 46 = 4 (NO2)4 = N4O8
0.575 L 1 mole
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 0.880 mol cpd 171.3 g cpd
x ------x ------= 113.058 g
1 L soln. 1 mol cpd
63. C20H27O6 An organic compound is known to contain 48.00 grams of carbon, 1.20 moles of oxygen atoms, and 3.25 x 1024 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 C : H : O
= (3.33 : 4.50 : 1.0) x 6
3.25 x 1024 atom H / Av# = 5.40 mol H
1.20 mol O 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 - 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.
66. B 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
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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