The Behavior of Gases—Review Guide Matching Column A 1. ideal gas constant (R) C 2. Boyle’s Law H 3. Dalton’s Law of partial pressures 4. ideal gas law G 5. combined gas law 6. Charles’s Law 7. Diffusion 8. partial pressure Column B a. the volume of a fixed mass of gas is directly proportional to the Kelvin temperature if the pressure is kept constant b. at constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the component gases F A E D B c. 0.0821 L x atm mol x K d. the contribution of each gas in a mixture make to the total pressure e. a gas tends to move to an area of lower concentration until the concentration is uniform throughout f. P1V 1 P 2V 2 T1 T2 g. PV = nRT h. For a given mass of gas at constant temperature, the volume of gas varies inversely with the pressure. Multiple Choice: 9. As the temperature of a fixed volume of gas increases, the pressure will: a) vary inversely b) decrease c) be unchanged d) increase. 10. A breathing mixture used by deep-sea divers contains helium, oxygen, and carbon dioxide. What is the partial pressure of oxygen at 101.3 kPa total pressure if PHe = 84.0 kPa and PCO2 = 0.10 kPa? a) 10.3 kPa b) 17.2 kPa c) 34.4 kPa d) 185.4 kPa 11. Increasing the volume of a given amount of gas at constant temperature caused the pressure to decrease because a) the molecules are striking a larger area with the same force b) there are fewer molecules c) the molcules are moving more slowly d) there are more molecules 12. The volume of a gas is doubled while the temperature is held constant. The pressure of the gas: a) remains unchanged b) is reduced by one half c) is doubled d) depends on the kind of gas 13. As the temperature of a gas in a balloon decreases a) the volume increases b) the pressure increases c) the average kinetic energy of the gas particles decreases d) all of the above are true 14. The volume of a gas is increased from 0.5 L to 4.0 L while the temperature is held constant. The pressure of the gas a) increases by a factor of four b) decreases by a factor of eight c) increases by a factor of eight d) increases by a factor of two 15. A gas occupies 40.0 mL at -123 °C. What volume does it occupy at 27 °C, assuming pressure is constant? a) 182 mL b) 8.80 mL c) 80.0 mL d) 20.0 mL 16. A gas occupies a volume of 0.2 L at 25 kPa. What volume will the gas occupy at 2.5 kPa? a) 4 L b) 20 L c) 2 L d) 0.02 L 17. Which of these changes would NOT cause an increase in the pressure of a contained gas? a) another gas is added to the container b) additional amounts of the same gas are added to the container c) the temperature is increased d) the gas is moved to a larger container 18. If a balloon containing 1000. L of gas at 50. °C and 101.3 kPa rises to an altitude where the pressure is 27.5 kPa and the temperature is 10. °C, its volume there is? (1000.L) x(101.3kPa) (V 2) x(27.5kPa) 323K 283K V2= 3227 L (sig figs ~ 3200 L) 19. Under the same conditions of temperature and pressure, what is the relative rate of effusion of chlorine gas compared to helium gas? Give your answer with two significant figures. RateCl RateHe MMHe 4.0 0.3 MMCl 35.45 20. A 10.0 g mass of krypton occupies 15.0 L at a pressure of 156 kPa. Find the volume of the krypton when the pressure is increased to 215 kPa at the same temperature. P1V1 = P2V2 (156kPa)(15.0L) = (215kPa)(V2) V2 = (156)(15) / (215) = 10.9 L 21. A gas has a volume of 550. mL at a temperature of –55.0 °C. What volume will the gas occupy at 30.0 °C, assuming constant pressure? V1 V 2 = T1 T 2 550ml V2 218 K 303K V2= (550)(303) / (218) = 764 ml 22. A 250. mL sample of fluorine gas is collected over water at 25.0 °C and 760. torr pressure. What is the pressure in torr of the dry fluorine gas alone? (Vapor pressure of water at 25.0 °C = 23.8 torr) PF = Patm – PH20 = 760 torr – 23.8 torr = 736 torr 23. What volume will 159.7g N2 gas occupy at 54.0 °C and 675 mm Hg? P = 675 mmHg x 1atm 0.89 atm 760mmHg V= ? 1mole = 5.70 moles 28.02 g R = 0.0821 (L x atm / mol x K) T = 54.0 C + 273 = 327 K n= 159.7g x PV= nRT V= nRT (5.70moles) x(0.0821atmL / mK ) x(327 K ) = 172L P (0.89atm)