CHM 130 Exam 4. Chapters 11, 13, and 14 (and some of 15)

CHM 130 Exam 4: Chapters 11, 13, and 14 (and some of 15) Show all work for calculation problems and clearly mark your final answer. _E__ 1. (5 pts) Which of the following describes properties of gases? a. They are compressible. b. They expand to fill a container. c. They take the shape of a container. d. The particles in a gas are far apart. e. All of the above are true. 2. (6 pts) Convert 694 torr to units of a) atm, b) mmHg, and c) psi. a. atm: 694 torr x (1 atm / 760 torr) = 0.913 atm b. mm Hg: 694 torr x (760 mm Hg / 760 torr) = 694 mm Hg c. psi:694 torr x (14.7 psi / 760 torr) = 13.4 psi 3. (6 pts) You have a 1.00 L bottle of gas (closed), with P = 0.444 atm and T = 295° C. If you raise the temperature to 395oC, will the pressure increase or decrease (circle one)? Calculate the new pressure. P1 / T1 = P2 / T2; 0.444 atm / (295 + 273) = P2 / (395 + 273) P2 = 0.522 atm 4. (6 pts) A sample of helium at 35oC, a volume of 0.25 L, and a pressure of 515 mm Hg is compressed to a volume of 0.50 L, will the pressure increase or decrease (circle one)? Calculate the final pressure. Use Boyle’s Law for a constant temperature case of the ideal gas law: P1V1 = P2V2 P2 = (515 mmHg)(0.25 L) / ( 0.50 L ) P2 = 260 mm Hg (or 0.34 atm) 5. (6 pts) A 6.35 L sample of carbon monoxide is collected at 55oC and 0.892 atm. What volume will the gas occupy at 1.05 atm and 21oC? P1V1 / T1 = P2 V2 / T2 (0.892 atm * 6.35 L) / (55 + 273) = (1.05 atm * x ) / (21 + 273) 0.0172689 = 0.0035714 x x = 4.85 L (3 or 4 sig figs) 6. (12 pts) True or False: Circle the appropriate letter for each statement below: a. T F Liquids have a constant shape and constant volume. b. T F London forces are the strongest type of intermolecular force. c. T F Intermolecular forces holding molecules together are weaker than chemical bonds. d. T F Nonpolar molecules will have Dipole-Dipole forces. e. T F Xe is predicted to have higher a boiling point than He. f. T F H2 is predicted to have a higher vapor pressure than H2O. 7. (4 pts) What is the strongest type of intermolecular force (London forces, Dipole-Dipole, or Hydrogen Bond Forces) in: CH4: ___London forces___ H2O: ___Hydrogen Bond Forces______ 8. (4 pts) Use the intermolecular force types of CH4 and H2O from the question above to determine the following properties below. a. Higher vapor pressure: __CH4___ b. Higher boiling point: __ H2O ____ c. Stronger surface tension: __H2O__ d. Higher viscosity: __ H2O ___ 9. (6 pts) What holds the following together? Your choices are nonpolar covalent bond (NPC), polar covalent bond (PC), ionic bond (I), London forces (LDF), Dipole-Dipole forces (DD), and Hydrogen Bond Forces (HBF). a. __PC_ N and O atoms in NO2. b. _HBF_ The molecules in ammonia. c. _NPC_ Chlorine atoms in Cl2. d. __I__ Li and Cl ions in a solid. e. _LDF_ Cl2 molecules in a gas. f. _DD__ Two CH2F2 molecules. _A__ 10. (5 pts) Which one of the following is an example of a metallic solid? a. Mg (s) b. CaCl2 (s) c. CO2 (s) 11. (6 pts) The graph to the right represents a temperature versus heat energy plot for a pure substance. Answer the following questions. a. What letter represents pure gas? _E___ b. What phase changes occur at letter B? __melting/freezing___________ c. What is the temperature of the boiling point of this substance? __60oC_____ d. What letter represents pure solid? _A__ 12. (8 pts) Complete the following table by d. P4 (s) determining if each solute will or will not mix with each solvent. Your choices for each combination are miscible, immiscible, soluble, or insoluble. Solvents () ZnSO4 (s) CH2F2 (l) S8 (s) Br2 (l) H2O (l) soluble miscible insoluble immiscible CCl4 (l) insoluble immiscible soluble miscible __C_ 13. a. b. c. d. (5 pts) A nitric acid solution that is 70.0% HNO3 by mass contains 70.0 g of HNO3 and 100.0 g water. 70.0 mol HNO3. 70.0 g HNO3 and 30.0 g water. 70.0 g HNO3 and 70.0 g water. 14. (5 pts) An oven cleaning solution is 40.0 % by mass of NaOH. If one jar of this product contains 454 grams of solution, how many grams of NaOH does it contain? Show all work. Mass solute / mass solution x 100 = (x g / 454 g) x 100 = 40.0% x = 454 g * 0.400 = 181.6 g = 182 g 15. (5 pts) If 160.20 grams of NH4Cl is dissolved in 4.00 L of water, what is the concentration (molarity) of the solution? 160.20 g x (1 mol / 53.5 g) = 2.994 mol NH4Cl / 4.00 L = 0.749 M _C__16. (5 pts) What is the term for a substance that donates a proton in an acid-base reaction? a. Arrhenius acid b. Arrhenius base c. Bronsted-Lowry acid d. Bronsted-Lowry base 17. (2 pts) In the following reaction, which reactant is a Bronsted-Lowry base? Circle your answer. NH3(aq) + H2O (l) NH4+ (aq) + OH- (aq) 18. (4 pts) What is the pH of a solution with [H+] = 1.0 x 10-3 M? __3.0____________ Is this solution acidic, basic, or neutral? ___acidic__________