by: Written Cassandra Wightman If there are any discrepancies or questions, feel free to e-mail me at [e-mail] LBS 172 Exam 1 Review Questions 1. If under certain condition, pressure is equal to 2.7 atm, convert the pressure into units of mm Hg, torr, kilopascals (kPa), and Pascals (Pa). 2100 mm Hg, 2100 torr, 270 kPa, 2.5 105 Pa 2. If V1 = 700 mL, P2 = 1.0 atm, V2 = 1750 mL, what is P1 equal to? 2.5 atm 3. Name and state the law relating temperature and volume. Charles' Law: (V1/T1) = (V2/T2) 4. Avogadro's Law, (V1/n1) = (V2/n2), relates number of moles and volume. For this law to hold true, what conditions must be constant? Pressure and temperature 5. What is the volume to 2.0 moles of gas assuming that both temperature and pressure are standard? 44.828 L 6. What is the density of H2O (g) at 380C and 720 torr? 0.589 g/L 7. 0.850 g Cl2 (g) and 0.163 g H2 (g) are in a 5.0 L vessel at 350C. The reaction produces only HCl. What is the final pressure in Pascals? In torr? 2.47 104 Pa. 186 torr 8. Find the root mean squared (weighted average speed) of a Br2 molecule under standard conditions. = [(3RT)/M], thus = 215.7 m/s 9. Explain the differences between gas diffusion and effusion. Diffusion is the gradual mixing of molecules of one gas with molecules of another while effusion is a process in which gases escape out of a small opening in a container. Although different in meaning, both relate speed with molar mass and show that at constant temperature and pressure, the speed of the gases is proportional to the inverse of the square root of the molar mass. 10. To solve for a variable in PV = nRT, all but the unknown variable must be known. It is also well-known that PV = nRT only refers to ideal gases. Why can this equation not be applied to non-ideal gases? PV = nRT assumes no interactions between collisions and that molecules have no volume. 11. T or F a. Water is a bent molecule that is formed by bonded molecules. F b. Intermolecular forces are stronger covalent than bonds. F c. Dipole-induced dipole forces are temporary forces that are weaker than dipoledipole forces. T d. London dispersion forces are only present in induced dipole-induced dipole forces. F 12. Explain why oil and water do not mix. H2O w/ H2O is lower E than w/ oil and oil w/ oil is lower E than w/ H2O. 13. Why is H2S more polarizable than H2O? H2S because the e- cloud is bigger because S is bigger than O. Bigger atoms are more polarizable. 14. In general as IMFs increases, boiling point ___________ (increases/decreases). increases 15. Why are oxygen, nitrogen, and fluorine the only elements that a hydrogen atom can bond to and bond to another O, N, or F on another molecule to cause hydrogen bonding? O, N, and F have the three highest EN values (). When they bond with H, highly polar bonds with H are created. O, N, and F are the smallest highest ed atoms.
16. Rank all IMFs present in NH3 from strongest to weakest. Hydrogen bonding, dipoledipole, London dispersion forces 17. T or F a. Hydrogen bonding is not actually bonding. T b. Hydrogen bonding can only occur with like-molecules, meaning NH3 can only have hydrogen bonds with other NH3 molecules. F c. Cohesive...