Chapter : Gasses. The atmospheric pressure of 768. mm Hg. Expressed in kilopascals (kpa) what would the value be the pressure? ( atm = 035 Pa = 760 torr = 760 mm Hg) a. 778.4 kpa b. 0.4 kpa c. 00.3 kpa d. 9.6 kpa e. 04 kpa 0.35 kpa = 760 mm Hg? 768. mm Hg P = 0.4 kpa. A sample of a gas occupied a volume of 6.44 liters when the pressure was 850 torr and the temperature was 7. C. The pressure was readjusted to 443 torr. What was the new volume? a. 0.837 L b. 0.937 L c..3 L d..53 L e. 3.34 L V =6.44 L P = 850 torr V =? L P = 443 torr P. V = P. V (850 torr) (6.44 L) =(V ) (443 torr) V =.3 L 3. A sample of a gas.40 liters when the pressure was 76 torr and the temperature was 6.9 C. The volume of the system was readjusted to 0.50 liters. What was the new pressure? a. 3.4 atm b. 883 atm c. 98 atm d. 00 atm e. 9.36 atm P. V = P. V (76 torr) (.40 L) =(x) (0.50 L) P = 7 torr P= 7 /760 = 9.36 atm
4. A sample of a gas occupied a volume of.40 liters when the pressure was 768 torr and the temperature was 6.9 C. The volume of the system was readjusted to.6 liters. What was the temperature in the system at this point? a. 4.5 º C b. 4.9 º C c. 89.8 º C d. 94.7 º C e. 88.6 º C V T V T T = V T / V.6 x (6.9+73.5) /.40 = 46.9 K 46.9 73.5 = 89.8 o C 5. STP for gases has the values; a. temperature: 0.00 K; pressure:.000 standard atmosphere b. temperature: 0.00 º C; pressure:.000 standard atmosphere c. temperature: 73.5 K; pressure:.000 Pascal d. temperature: 98.5 K; pressure:.000 standard atmosphere e. temperature: 98.5 K; pressure:.000 Pascal 6. The volume of gas was.54 liters at 8.40 C, and 637.6 torr. What volume would this gas sample occupy at STP? a..069 L b..58 L c..4 L d..645 L e..006 L STP : P = 760 torr and T =73 K P. V / T = P. V / T V = (P V T ) / (P T ) V = 637.6 x.54 x 73 / 760 x 30.55 V =.58 L 7. How many liters of pure oxygen gas, measured at STP, are required for the complete combustion of. L of CH 4 gas, also measured at STP? CH 4 + O CO + H O L L. L? L V=. x / =.4 L a.. L b. 6.8 L c..4 L d. 3.0 L e. 33.6 L
8. A chemical reaction is shown: NO(g) + O (g) NO (g). How many liters of pure oxygen gas, measured at STP, are required for the complete reaction with 8.8 L of NO(g), also measured at STP? a. 4.4 L b. 8.8 L c.. L d. 7.6 L e..4 L NO(g) + O (g) NO (g) L L 8.8 L? L V= 8.8 / = 4.4 L 9. A gas sample weighing 3.78 grams occupies a volume of.8 L at STP. What is the molecular mass of the sample? PV = mrt/ = mrt/pv = [(3.78 g) (0.0806 L atm mol K ) (73)] / [ atm) (.8 L) = 30.6 g mol a. 8.54 g mol - b. 3.5 g mol - c. 37. g mol - d. 5. g mol - e. 93 g mol - 0. Two moles of CO gas at 35 C are heated to 50 C, The density of the gas in the gas will: P. = d.r.t The Density is inversely proportional to Temperature T increases, Density decreases a. increase. b. decrease. c. remain the same. d. There is not enough information given to correctly answer this question.. What volume would. g of a gaseous compound occupy at STP if its molecular weight is 44.0 g/mole? P V = m R T / V = m R T / P V = [(. g) (0.0806 L atm mol K ) (73)] / [ atm) (44.0 g/mole) V = 5.7 L 3
a. 5.7 liters b..0 liters c.. liters d..4 liters e. 44.0 liters. A gas sample occupies a volume of.66 L when the temperature is 50.0 C and the pressure is 84 torr. How many molecules are in the sample? n = p.v/rt n= (84/760)atm x.66 L / 0.0806 L atm mol K (50+73.5 K) n=0.053 mol N= n x N A = 0.053 x 6.0 x 0 3 = 3.9 x 0 molecules a..5 0 b..60 0 c. 3.9 0 d. 9.0 0 e. 9.4 0 3. A gas container has a volume of 6.504 L. When filled with C 3 H 8, at 8.3 C, the pressure is 486.3 torr. How much should the gas sample weigh? P V = m R T / m = P.V. / R T m = (486.3/760)atm x 6.504 L x (44 g/mol) / 0.0806 L atm mol K (8.3 + 73.5 K) m = 7.4 g a. 4.67 g b. 7.4 g c. 7.5 g d. 8. g e. 63. G 4. A container contains 0. moles of O gas and 0.3 moles of N gas. If the total pressure is 0.75 atm what is the partial pressure of O? P i =X i. P t P i = (n i / n T ). P t P i = (0. / 0.5 ) 0.75 P i = 0.30 atm a. 0.0 atm b. 0.30 atm c. 0.50 atm d. 0.75 atm e. 0.45 atm 4
5. A container contains partial pressures of 0.80 atm CO gas and 0.35 atm N gas. What is the mole fraction of N in the glass container? X i = P i / P t X i = 0.35 / (0.8 + 0.35) X i = 0.30 a. 0.35 b..5 c. 0.70 d. 0.80 e. 0.30 6. A gaseous substance diffuses twice as rapidly as SO gas. The gas could be a. CO b. He c. H d. CH 4 e. O r r 64 4 3 3 64 6g / mol 4 7. According to the kinetic theory of gases, the average kinetic energy of the gas particles in a gas sample is directly proportional to the; a. pressure. b. volume. c. absolute temperature. d. molar mass. e. number of moles of gas. n a V nb 8. The van der Waals equation of state for a real gas is: P nrt V At what pressure will.00 mole of CH 4 be in a 0.0 L container at 98 K assuming CH 4 is a real gas. (van der Waals constants for CH 4 are a =.53 L atm mol -, b = 0.0478 L mol - ) a..43 atm b..8 atm c..5 atm d. 4.5 atm e. 0.440 atm 5
9. A real gas behaves most nearly like an ideal gas under conditions of a. low temperature and high pressure. b. low temperature and low pressure. c. high temperature and low pressure. d. high temperature and high pressure. e. Actually it will behave like an ideal gas regardless of the temperature or the pressure as long as it remains in the gaseous state. 6