Sample Exam 3 – Chapters 8, 9, 10

Name: _______KEY__________ Sample Exam 3 – Chapters 8, 9, 10 Show ALL work for FULL credit!! 1. Which of the following substances crystallizes as a molecular solid? a. NaCl b. CO2 c. Au d. K2CO3 e. CaO 2. Circle ALL of the IMF’s present for each of the following substances: A. B. C. D. LDF DDF HBF LDF DDF HBF LDF DDF HBF LDF DDF HBF 3. Which of the following properties indicates the presence of weak intermolecular forces in a liquid? a. a high boiling point b. a high vapor pressure c. a high viscosity d. a high surface tension 4. Which of the following should have the highest boiling point at a given temperature? a. methane, CH4 b. carbon tetrafluoride, CF4 c. carbon tetrachloride, CCl4 d. carbon tetrabromide, CBr4 e. carbon tetraiodide, CI4 5. Refer to the phase diagram provided to answer the following questions: a. What is the normal boiling point for this substance? 105ºC b. What is the physical state for this substance at 1.5 atm and 150°C? liquid c. Circle the vaporization curve on the phase diagram below. 6. Calculate the heat of reaction, ΔH°, for the reaction: 3 NO2 (g) + H2O (l) → 2 HNO3 (aq) + NO (g) Substance: ΔH°f (kJ/mol) NO2(g) 33.2 H2O (l) -285.5 HNO3 (aq) -119.0 NO (g) 91.3 ΔHºrxn = 39.2 kJ 7. Determine the amount of heat released when 26.9 mL methanol, CH3OH (density = 0.792 g/mL), reacts according to the following combustion equation: 2 CH3OH (l) + 3 O2 (g) → 2 CO2 (g) + 4 H2O (l) ΔH°rxn = -1452.8 kJ/mol ΔHºrxn = -483 kJ 8. Use the given average bond dissociation energies to estimate ΔH for the reaction of methane, CH4 (g), with fluorine: ____ CH4 (g) + __2__ F2 (g) → ____ CF4 (g) + __2__ H2 (g) Bond EBDE, kJ/mol H-H 436 C-F 450 ΔHºrxn = -716 kJ C-H 410 F-F 158 9. List the following ionic compounds in order of increasing lattice energy: Li3P, Sr3P2, Mg3P2, AlP, Lowest LE _Li3P__ > __Sr3P2_ > __Mg3P2__ > __AlP__ > Highest LE 10. Which of the following equations represents a heat of formation equation? a. C (s) + O2 (g) → CO2 (g) b. 2 Au (s) + 3 Cl2 (g) → 2 AuCl3 (s) c. Cl (g) + Na (s) → NaCl (s) d. CaO (s) + CO2 (g) → CaCO3 (s) 11. What type of bond typically has the highest bond enthalpy value? a. single b. double c. triple d. all three have the same value for bond enthalpy 12. Which of the following has a standard enthalpy of a formation value (ΔHf°) of zero? H2O (l) O3 (g) Br2 (l) O (g) CO2 (s) 13. Which ionic compound is the most stable? a. CaO b. K2O c. SrO d. Rb2O 14. When bonds are broken in a chemical reaction, this process is considered _________________. a. exothermic b. endothermic 15. Find ΔH for BaCO3 (s) → BaO (s) + CO2 (g) given 2 Ba (s) + O2 (g) → 2 BaO (s) Ba (s) + CO2 (g) + ½ O2 (g) → BaCO3 (g) ΔH = -1107.0 kJ ΔH = -822.5 kJ ΔH = 269.0 kJ 16. Which one of the following is not used to describe the condition of a gas? a. number of moles b. polarity c. temperature d. volume 17. Boyle’s Law states that pressure is a. directly related to volume b. inversely related to volume c. directly related to temperature d. inversely related to temperature 18. A basketball is inflated to a pressure of 1.50 atm in a 20.0°C garage. What is the pressure of the basketball outside where the temperature is -5.0°C? (Assume V and n are constant) a. 1.37 atm b. 1.42 atm c. 1.58 atm d. 1.64 atm 19. Which of the following would have a density of 1.21 g/L at 280.15°C and 0.993 atm? a. Ar b. N2 c. Ne d. O2 20. What is the total pressure in a 3.00 L container containing 0.310 moles of N2 and 0.250 mole of O2 at 303 K? a. 4.64 atm b. 4.55x10-4 atm c. 0.215 atm d. 1.00 atm 21. Which of the following gases has the highest average speed at 400K? a. CO2 b. N2O4 c. F2 d. SF6 22. A process by which gas molecules escape through a tiny hole in a membrane into a vacuum without collisions is called a. Boyle's law. b. diffusion. c. sublimation. d. effusion. 23. Of the following statements, which describes properties of an ideal gas? a. Gases are highly compressible. b. There are relatively large distances between gas molecules in a container. c. Gases form homogeneous mixtures and do not react with other gas molecules. d. All of the above. 24. The specific capacity heat of copper is 0.385 J/(g°C). If 34.2 g of copper, initially at 25°C, absorbs 4.689 kJ, what will be the final temperature of the copper? a. 356 °C b. 381 °C c. 25.4 °C d. 27.8 °C 25. What mass of chlorine gas occupies a 4.50L container at 55.6ºC and 887 torr? PV=nRT solve for n = 0.19468 moles Cl2 Now use molar mass to get grams = 13.8 gCl2 26. What volume of hydrogen gas is produced when 6.75 g of aluminum is placed in excess 4.0 M HCl at 33.8 ºC and 956.4 torr according to the equation 2Al(s) + 6HCl(aq) → 3H2(g) + 2AlCl3(aq)? 6.75 g Al( 1 mol Al )( 3 mol H2) = 0.375 mol H2 (26.98 g Al)(2 mol Al ) PV=nRT V = nRT = (0.375 mol H2)(0.08206 L atm mol-1 K-1)(306.95K)= 7.51 L P (1.2584 atm) 27. How much heat is absorbed when 30.00 g of C (s) reacts in the presence of excess SO2 (g) to produce CS2 (l) and CO (g) according to the following chemical equation? 5 C (s) + 2 SO2 (g) → CS2 (l) + 4 CO (g) ΔH° = +239.9 kJ 30.00 g C ( 1 mol C )(239.9 kJ )= 119.9 kJ (12.011 g C)( 5 mol C) 28. Which of the following would exhibit dipole-dipole forces as the strongest force between molecules? a. HCN b. CCl4 c. CH3OH d. C6H6 29. Which of the following will have the lowest boiling point? a. CH3CH2CH2NH2 b. CH3CH2CH2SH c. CH3CH2CH2OH 30. Solid carbon dioxide, CO2 (s), is what type of crystalline solid? a. molecular b. ionic c. metallic 31. What type of intermolecular force, IMF, would be present between molecules in a sample of Br2 (l)? a. LDF b. DDF c. HBF d. Ion-Dipole Forces 32. What is the strongest IMF present between like molecules in a sample of H2S (l)? a. LDF b. DDF c. HBF d. Ion-Dipole Forces 33. What type of bond is present between atoms in a sample of CO2? a. nonpolar covalent b. polar covalent c. LDF d. James 34. Hexane, C6H12, is an organic molecule found in gasoline. Circle the property of liquids that would have a relatively high value for hexane. a. vapor pressure b. surface tension c. boiling point d. viscosity 35. Which molecule will have the highest boiling point? a. I2 b. Br2 36. Select the correct molecule with the lowest surface tension. a. CH3CH2CH2Cl b. CH3CH2CH2NH2 c. Cl2 d. F2 c. CH3CH2CH2CH3 37. Select the molecule that has HBF as it’s strongest IMF between like molecules. a. CH3CH2CH2SH b. CH3CH2CH2OH c. CH3CH2OCH2CH3 38. What is the strongest force present between like particles in a sample of liquid mercury, Hg (l)? a. London Dispersion Forces b. Ionic Bonds c. Covalent Bonds d. Metallic Bonds