Chem 101 General Chemistry Practice Final Exam

Transcription

1 Name h = x J s (Planck s Constant) c = 3.00 x 10 8 m/s (speed of light) R H = x 10-7 m -1 (Rydberg Constant) Chem 101 General Chemistry Practice Final Exam Multiple Choice (5 points each) Identify the letter of the choice that best completes the statement or answers the question and legibly write the letter in the space preceding the problem number. 1. Which of the following is not a solution? a. red wine b. alcohol in water c. brass d. air e. ice in water 2. Which of the following statements concerning the atom is false? a. Chemical reactions involve only the electrons. b. The atom contains protons, neutrons and electrons. c. Protons are found in orbits about the nucleus. d. The nucleus contains both protons and neutrons. e. Most of the mass of the atom is found in the nucleus. 3. Which of the following statements about two isotopes is false? a. They will have the same charge on the nucleus. b. They will have different numbers of neutrons. c. They will have essentially the same chemical reactivity. d. They will have the same atomic numbers. e. They will have the same atomic weights. 4. Which element can be classified as an alkaline earth metal? a. Al b. Mg c. Ag d. Au e. Na 5. Which combination below corresponds to a cation with a +1 charge? a. 7 protons and 8 electrons b. 11 protons and 10 electrons c. 18 protons and 18 electrons d. 17 protons and 18 electrons e. 20 protons and 18 electrons

2 6. When 2.34 g of pure iron is allowed to react with an excess of oxygen, 3.35 g of the final compound is produced. Determine the formula of the compound. a. Fe 2 O 3 b. FeO c. FeO 2 d. FeO 3 e. FeO 4 7. The complete combustion of a hydrocarbon produces g of CO 2 and g of H 2 O. What is the empirical formula of the hydrocarbon? a. CH b. CH 2 c. C 2 H 5 d. C 3 H 8 e. C 3 H 4 8. Ammonia and sulfuric acid react according to the equation given below. How many milliliters of M sulfuric acid are required to exactly neutralize 25.0 ml of M NH 3 solution? 2 NH 3 (aq) + H 2 SO 4 (aq) (NH 4 ) 2 SO 4(aq) a ml b ml c ml d ml e ml 9. Determine if each of the four situations below describes kinetic or potential energy. I a moving bullet II picture hanging on a wall III the bonds in a mixture of H 2 and O 2 IV the movement of molecules I II III IV a. potential kinetic kinetic potential b. potential potential kinetic kinetic c. kinetic potential kinetic potential d. kinetic kinetic potential potential e. kinetic potential potential kinetic 10. What is the molar heat capacity of table salt, NaCl (specific heat = 0.88 J g -1 C -1 )? a J mol -1 C -1 b J mol -1 C -1 c J mol -1 C -1 d. 117 J mol -1 C -1 e. 245 J mol -1 C -1

3 11. A sample of water containing 2.00 moles is initially at 30.0 C. If the sample absorbs 2.00 kj of heat, what is the final temperature of the water? (specific heat of water = J g -1 C -1 ) a C b C c C d C e. 269 C 12. What is the enthalpy change when 225 g of C 2 H 2 are burned in excess O 2? C 2 H 2(g) + 5/2O 2(g) 2CO 2(g) + H 2 O (l) ΔH = kj a kj b kj c kj d kj e kj 13. Determine the heat of reaction for the process TiO 2(s) + 4HCl (g) TiCl 4(l) + 2H 2(g) + O 2(g) using the information given below: Ti (s) + O 2(g) TiO 2(s) ΔH = kj 2HCl (g) H 2(g) + Cl 2(g) ΔH = kj Ti (s) + 2Cl 2(g) TiCl 4(l) ΔH = kj a kj b kj c kj d kj e kj 14. Which of the following is not a characteristic of the Bohr model of the atom? a. An electron is located in an orbit around the nucleus. b. Each orbit has a discrete energy associated with it. c. Orbits have defined radii. d. There is a continuum of energy levels that an electron can have around a nucleus. e. Orbits have a defined circumference. 15. Which azimuthal quantum numbers can exist for n = 3? a. l = 0 b. l = 0, 1 c. l = 0, 1, 2 d. l = 0, 1, 2, 3 e. l = 0, 1, 2, 3, 4

4 16. If l = 1, what value can m l have? a. m l = -1 b. m l = +1 c. m l = 0, +1 d. m l = 0 e. m l = -1, 0, How many electrons can the second principal quantum level hold? a. 2 b. 8 c. 16 d. 18 e Which of the following has the electron configuration 1s 2 2s 2 2p 6 3s 2 3p 6? a. Ca b. Cl c. Ar d. K + e. Both c and d 19. Which element has the largest atomic radius? a. F b. He c. O d. H e. Na 20. Which element will have five electrons in its Lewis symbol? a. beryllium b. neon c. oxygen d. carbon e. nitrogen 21. Which molecule does not contain a double bond? a. CO 2 b. CH 2 O c. O 2 d. HCOOH e. HCN 22. Write the correct Lewis dot structure for CO. Which statement correctly describes the structure? a. The structure contains 1 single bond and 6 lone pairs. b. The structure contains 1 single bond and 7 lone pairs. c. The structure contains 1 double bond and 4 lone pairs. d. The structure contains 1 double bond and 5 lone pairs. e. The structure contains 1 triple bond and 2 lone pairs.

5 23. Write the correct Lewis dot structures for the compounds given below. Arrange them in order of shortest to longest bond lengths. Consider only the carbon-carbon and carbon-oxygen bonds. C 2 H 2 C 2 H 6 C 2 H 4 CO a. C 2 H 6 < C 2 H 4 < C 2 H 2 < CO b. C 2 H 2 < CO < C 2 H 4 < C 2 H 6 c. C 2 H 2 < C 2 H 4 < C 2 H 6 < CO d. CO < C 2 H 2 < C 2 H 4 < C 2 H 6 e. CO < C 2 H 6 < C 2 H 4 < C 2 H From the data given below, calculate the approximate enthalpy change of reaction for the reaction below. CH 4 (g) + 2O 2 (g) CO 2 (g) + 2H 2 O(g) bond enthalpy kj/mol C-H 414 C-C 347 C=C 611 C-O 351 C=O 803 O-H 463 O=O 498 H-H 436 a kj b. -98 kj c. 98 kj d. 120 kj e. 806 kj 25. Which statement properly describes the formal charges on the atoms in? a. +2 on sulfur, -2 on oxygen b. +2 on sulfur, -1 on oxygen c. +1 on sulfur, -1 on oxygen d. -1 on sulfur, +2 on oxygen e. -2 on sulfur, 0 on oxygen 26. (15 points) Which species has a greater ionization energy: Ne or Na +? Explain why.

6 27. (15 points) List the following atoms in the correct order of increasing (smallest to largest) atomic radii: Bromine (Br), Fluorine (F), Sulfur (S), Arsenic (As) 28. (15 points) Draw the Lewis structure of carbonic acid, H 2 CO 3, and determine the formal charge of each atom in the structure. 29. (15 points) Draw the molecular orbital energy diagram for nitrogen monoxide, NO, and determine the bond order of the molecule. (Reminder: place the atomic orbitals at appropriate relative energies based on the electronegativity of the nitrogen and oxygen.)

7 30. (15 points) Iodine (I 2 ) is a solid at room temperature but sublimes easily ΔH o sub = kj/mol. If g of I 2 (s) is irradiated with 510 nm light, how many photons are required to vaporize this amount of iodine?