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Honors Chemistry Chapter Nine PracticeExam Student: ___________________________________________________________________________ 1. Which of these compounds is most likely to be ionic? A. KF B. CCl4 C. CS2 D. CO2 E. ICl 2. Which of these compounds is most likely to be ionic? A. NCl3 B. BaCl2 C. CO D. SO2 E. SF4 3. Which of these compounds is most likely to be covalent? A. Rb2S B. SrCl2 C. CS2 D. CaO E. MgI2 4. Which of these compounds is most likely to be covalent? A. CsOH B. NF3 C. Sr(NO3)2 D. CaO E. LiF 5. The Lewis dot symbol for the chloride ion is A. B. C. D. E. 6. Which of these ionic solids would have the largest lattice energy?
A. NaCl B. NaF C. CaBr2 D. CsI E. CaCl2 7. Which of these solids would have the highest melting point? A. NaF B. NaCl C. NaBr D. NaI 8. Which of these solids would have the lowest melting point? A. KI B. KBr C. KCl D. KF 9. Which of these atom is the most electronegative? A. Li B. Cs C. P D. As E. Ge 10. A polar covalent bond would form in which one of these pairs of atoms? A. B. C. D. E. 11. A nonpolar covalent bond (i. e. , pure covalent) would form in which of these pairs of atoms? A. B. C. D. E. 12. Which of these covalent bonds is the most polar (i. e. , highest percent ionic character)? A.
B. C. D. E. 13. In which of these pairs of atoms would the bond be the most polar? A. B. C. D. E. 14. The electron dot formula for O2 shows A. a single covalent bond. B. a double covalent bond. C. an ionic bond. D. a total of 8 2 = 16 electron dots. E. a total of 32 electron dots. 15. The electron dot structure for AsCl3 shows A. a total of 84 electron dots. B. three single bonds and 10 lone pairs. C. two single bonds, one double bond, and 9 lone pairs. D. one single bond, two double bonds, and 8 lone pairs. E. three single bonds and one lone pair. 16. The total number of lone pairs in NCl3 is
A. 6. B. 8. C. 9. D. 10. E. 13. 17. The Lewis structure for a chlorate ion, ClO3-, should show ____ single bond(s), ____ double bond(s), and ____ lone pair(s). A. 2, 1, 10 B. 3, 0, 9 C. 2, 1, 8 D. 3, 0, 10 E. 2, 1, 9 18. Which of these choices is a correct Lewis structure for ozone, O3? A. B. C. D. E. 19. The number of resonance structures for the nitrate ion that satisfies the octet rule is A. 1. B. 2. C. 3. D. 4. E. none of these. 20. The azide ion, N3-, is very reactive although it is isoelectronic with the very stable CO2 molecule. This reactivity is reasonable because A. Lewis structure cannot be written for the azide ion that has nitrogen formal charges of zero. B. there is no valid Lewis structure possible for the azide ion. C. there are resonance structures for azide ion but not for carbon dioxide. D. nitrogen cannot form multiple bonds. E. charged species always decompose in solution. 21. Which of these statements is a useful guideline for the application of formal charges in neutral molecules? A. A Lewis structure in which there are no formal charges is preferred. B. Lewis structures with large formal charges (e. g. , +2,+3 and/or -2,-3) are preferred. C.
The preferred Lewis structure is one in which positive formal charges are on the most electronegative atoms. 22. The formal charge on the bromine atom in BrO3- drawn with three single bonds is A. -2. B. -1. C. 0. D. +1. E. +2. 23. What is the formal charge on sulfur in the best Lewis structure for the SCN- (thiocyanate) ion? A. +2 B. -2 C. +1 D. -1 E. 0 24. What is the formal charge on phosphorus in a Lewis structure for the phosphate ion that satisfies the octet rule? A. -2 B. -1 C. 0 D. +1 E. +2 25. In the best Lewis structure for the fulminate ion, CNO-, what is the formal charge on the central nitrogen atom?
A. +2 B. +1 C. 0 D. -1 E. -2 26. Each of the three resonance structures of NO3- has how many lone pairs of electrons? A. 7 B. 8 C. 9 D. 10 E. 13 27. The total number of lone pairs in the best Lewis structure for the SOF4 molecule is A. 0. B. 2. C. 14. D. 16. E. 18. 28. Which of these elements is most likely to exhibit an expanded octet in its compounds? A. O B. S C. Na D. C E. N 29. Which of these molecules has an atom with an incomplete octet? A. NF3 B. H2O C. AsCl3 D. GeH4 E. BF3 30. Estimate the enthalpy change for the reaction 2CO + O2 2CO2 given the following bond energies. BE(CO) = 1074 kJ/mol
BE(O=O) = 499 kJ/mol BE(C=O) = 802 kJ/mol A. +2380 kJ/mol B. +744 kJ/mol C. +1949 kJ/mol D. -561 kJ/mol E. -744 kJ/mol 31. Use bond energies to estimate the enthalpy of formation of HBr(g). BE(H-H) = 436 kJ/mol BE(Br-Br) = 192 kJ/mol BE(H-Br) = 366 kJ/mol A. +262 kJ/mol B. -52 kJ/mol C. -104 kJ/mol D. +104 kJ/mol E. +52 kJ/mol 32. Use the bond enthalpy data given to estimate the heat released when 6. 50 g of nitrogen gas reacts with excess hydrogen gas to form ammonia at 25C. BE(NN) = 941. 4 kJ/mol BE(H-H) = 436. 4 kJ/mol BE(N-H) = 393 kJ/mol A. 228 kJ B. 340 kJ C. 107 kJ D. 46. 1 kJ E. 24. 9 kJ 33.
Use the bond enthalpy data given to estimate the heat released when 25. 0 g of acetylene gas, C2H2, burns in excess oxygen to yield carbon dioxide and water vapor at 25C. BE(C-C) = 347 kJ/mol BE(CC) = 812 kJ/mol BE(C=O in CO2) = 799 kJ/mol BE(C-H) = 414 kJ/mol BE(O-H) = 460 kJ/mol BE(O=O) = 498. 7 kJ/mol A. 1180 kJ B. 447 kJ C. 364 kJ D. 1230 kJ E. 16. 8 kJ Honors Chemistry Chapter Nine PracticeExam Key 1. Which of these compounds is most likely to be ionic? A. KF b. CCl4 c. CS2 d. CO2 e. ICl Chang – 009 Chemical… #1 Difficulty: Easy 2. Which of these compounds is most likely to be ionic? a. NCl3
B. BaCl2 c. CO d. SO2 e. SF4 Chang – 009 Chemical… #3 Difficulty: Easy 3. Which of these compounds is most likely to be covalent? a. Rb2S b. SrCl2 C. CS2 d. CaO e. MgI2 Chang – 009 Chemical… #5 Difficulty: Easy 4. Which of these compounds is most likely to be covalent? a. CsOH B. NF3 c. Sr(NO3)2 d. CaO e. LiF Chang – 009 Chemical… #7 Difficulty: Easy 5. The Lewis dot symbol for the chloride ion is a. B. c. d. e. Chang – 009 Chemical… #11 Difficulty: Medium 6. Which of these ionic solids would have the largest lattice energy? a. NaCl b. NaF c. CaBr2 d. CsI E. CaCl2 Chang – 009 Chemical… 13 Difficulty: Medium 7. Which of these solids would have the highest melting point? A. NaF b. NaCl c. NaBr d. NaI Chang – 009 Chemical… #15 Difficulty: Medium 8. Which of these solids would have the lowest melting point? A. KI b. KBr c. KCl d. KF Chang – 009 Chemical… #17 Difficulty: Medium 9. Which of these atom is the most electronegative? a. Li b. Cs C. P d. As e. Ge Chang – 009 Chemical… #23 Difficulty: Medium 10. A polar covalent bond would form in which one of these pairs of atoms? a. b. c. d. E. Chang – 009 Chemical… #27 Difficulty: Medium 11. A nonpolar covalent bond (i. e. pure covalent) would form in which of these pairs of atoms? a. b. c. d. E. Chang – 009 Chemical… #29 Difficulty: Medium 12. Which of these covalent bonds is the most polar (i. e. , highest percent ionic character)? a. b. C. d. e. Chang – 009 Chemical… #31 Difficulty: Medium 13. In which of these pairs of atoms would the bond be the most polar? a. b. c. D. e. Chang – 009 Chemical… #33 Difficulty: Medium 14. The electron dot formula for O2 shows a. a single covalent bond. B. a double covalent bond. c. an ionic bond. d. a total of 8 2 = 16 electron dots. e. a total of 32 electron dots.
Chang – 009 Chemical… #39 Difficulty: Medium 15. The electron dot structure for AsCl3 shows a. a total of 84 electron dots. B. three single bonds and 10 lone pairs. c. two single bonds, one double bond, and 9 lone pairs. d. one single bond, two double bonds, and 8 lone pairs. e. three single bonds and one lone pair. Chang – 009 Chemical… #41 Difficulty: Medium 16. The total number of lone pairs in NCl3 is a. 6. b. 8. c. 9. D. 10. e. 13. Chang – 009 Chemical… #43 Difficulty: Medium 17. The Lewis structure for a chlorate ion, ClO3-, should show ____ single bond(s), ____ double bond(s), and ____ lone pair(s). . 2, 1, 10 b. 3, 0, 9 c. 2, 1, 8 D. 3, 0, 10 e. 2, 1, 9 Chang – 009 Chemical… #45 Difficulty: Difficult 18. Which of these choices is a correct Lewis structure for ozone, O3? a. b. c. D. e. Chang – 009 Chemical… #47 Difficulty: Medium 19. The number of resonance structures for the nitrate ion that satisfies the octet rule is a. 1. b. 2. C. 3. d. 4. e. none of these. Chang – 009 Chemical… #49 Difficulty: Difficult 20. The azide ion, N3-, is very reactive although it is isoelectronic with the very stable CO2 molecule. This reactivity is reasonable because A. Lewis structure cannot be written for the azide ion that has nitrogen formal charges of zero. b. there is no valid Lewis structure possible for the azide ion. c. there are resonance structures for azide ion but not for carbon dioxide. d. nitrogen cannot form multiple bonds. e. charged species always decompose in solution. Chang – 009 Chemical… #51 Difficulty: Difficult 21. Which of these statements is a useful guideline for the application of formal charges in neutral molecules? A. A Lewis structure in which there are no formal charges is preferred. b. Lewis structures with large formal charges (e. g. , +2,+3 and/or -2,-3) are preferred. . The preferred Lewis structure is one in which positive formal charges are on the most electronegative atoms. Chang – 009 Chemical… #53 Difficulty: Easy 22. The formal charge on the bromine atom in BrO3- drawn with three single bonds is a. -2. b. -1. c. 0. d. +1. E. +2. Chang – 009 Chemical… #55 Difficulty: Medium 23. What is the formal charge on sulfur in the best Lewis structure for the SCN- (thiocyanate) ion? a. +2 b. -2 c. +1 d. -1 E. 0 Chang – 009 Chemical… #57 Difficulty: Difficult 24. What is the formal charge on phosphorus in a Lewis structure for the phosphate ion that satisfies the octet rule? . -2 b. -1 c. 0 D. +1 e. +2 Chang – 009 Chemical… #59 Difficulty: Difficult 25. In the best Lewis structure for the fulminate ion, CNO-, what is the formal charge on the central nitrogen atom? a. +2 B. +1 c. 0 d. -1 e. -2 Chang – 009 Chemical… #61 Difficulty: Difficult 26. Each of the three resonance structures of NO3- has how many lone pairs of electrons? a. 7 B. 8 c. 9 d. 10 e. 13 Chang – 009 Chemical… #65 Difficulty: Medium 27. The total number of lone pairs in the best Lewis structure for the SOF4 molecule is a. 0. b. 2. C. 14. d. 16. e. 18. Chang – 009 Chemical… #67
Difficulty: Difficult 28. Which of these elements is most likely to exhibit an expanded octet in its compounds? a. O B. S c. Na d. C e. N Chang – 009 Chemical… #69 Difficulty: Easy 29. Which of these molecules has an atom with an incomplete octet? a. NF3 b. H2O c. AsCl3 d. GeH4 E. BF3 Chang – 009 Chemical… #73 Difficulty: Medium 30. Estimate the enthalpy change for the reaction 2CO + O2 2CO2 given the following bond energies. BE(CO) = 1074 kJ/mol BE(O=O) = 499 kJ/mol BE(C=O) = 802 kJ/mol a. +2380 kJ/mol b. +744 kJ/mol c. +1949 kJ/mol D. -561 kJ/mol e. -744 kJ/mol Chang – 009 Chemical… #77
Difficulty: Difficult 31. Use bond energies to estimate the enthalpy of formation of HBr(g). BE(H-H) = 436 kJ/mol BE(Br-Br) = 192 kJ/mol BE(H-Br) = 366 kJ/mol a. +262 kJ/mol B. -52 kJ/mol c. -104 kJ/mol d. +104 kJ/mol e. +52 kJ/mol Chang – 009 Chemical… #79 Difficulty: Difficult 32. Use the bond enthalpy data given to estimate the heat released when 6. 50 g of nitrogen gas reacts with excess hydrogen gas to form ammonia at 25C. BE(NN) = 941. 4 kJ/mol BE(H-H) = 436. 4 kJ/mol BE(N-H) = 393 kJ/mol a. 228 kJ b. 340 kJ c. 107 kJ d. 46. 1 kJ E. 24. 9 kJ Chang – 009 Chemical… #81 Difficulty: Difficult 3. Use the bond enthalpy data given to estimate the heat released when 25. 0 g of acetylene gas, C2H2, burns in excess oxygen to yield carbon dioxide and water vapor at 25C. BE(C-C) = 347 kJ/mol BE(CC) = 812 kJ/mol BE(C=O in CO2) = 799 kJ/mol BE(C-H) = 414 kJ/mol BE(O-H) = 460 kJ/mol BE(O=O) = 498. 7 kJ/mol A. 1180 kJ b. 447 kJ c. 364 kJ d. 1230 kJ e. 16. 8 kJ Chang – 009 Chemical… #83 Difficulty: Difficult Honors Chemistry Chapter Nine PracticeExam Summary Category|# of Questions| Chang – 009 Chemical… |33| Difficulty: Difficult|11| Difficulty: Easy|6| Difficulty: Medium|16|

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