107Gases and theKinetic-MolecularTheory1212-1Pressure is a measure of a force applied per square unit of surface area. Pressure is the force per unitarea of a gas (or other fluid) confined to a container.12-3A mercury barometer consists of a glass tube, sealed at one end, filled with mercury, and then invertedinto a dish of mercury. The mercury in the tube falls until the pressure due to its height matches thepressure due to the air (the atmosphere) on the surface of the mercury in the dish. The height of themercury column is a measure of the external air pressure.12-5(a)? mm Hg = 675 torr x 1 mm Hg1 torr= 675 mm Hg(b)? atm = 675 torr x 1 atm760. torr= 0.888 atm(c)? Pa = 675 torr x 1 atm760. torrx 1.013 x 105Pa1 atm= 9.00 x 104Pa(d)? kPa = 9.00 x 104Pa x 1 kPa1000 Pa= 90.0 kPa12-7We use conversion factors based on the equivalences 1 atm = 760 torr = 101.3 kPa.atmtorrPakPaStandard atmosphere17601.013 x 105101.3Partial pressure of nitrogen inthe atmosphere0.7805937.90 x 10479.0A tank of compressed hydrogen1.591.21 x 1031.61 x 1051.61 x 102Atmospheric pressure at thesummit of Mt. Everest0.3332533.37 x 10433.712-9The height of liquid is inversely proportional to its density; the lower the density of the liquid, thetaller the column would be.height of oil column = 760. mm Hg x13.5 g/mL0.92 g/mLx1 m1000 mm= 11 m12-1131 psi x1 atm14.70 psi= 2.1 atm guage pressuretotal pressure = 1.0 atm + 2.1 atm = 3.1 atm
10812-13Yes, because for a given substance, the number of moles is directly proportional to the mass ofsubstance.12-15V = 2.50 L x 1.00 atm2.50 atm= 1.00 L12-17P1= 0.500 atmV1= 75.0 mLP2is given in each partV2= ?For each part, we use Boyle’s Law, P1V1= P2V2or V2= P1V1P2(a)V2= 0.500 atm x 75.0 mL5.00 atm= 7.50 mL(b)V2= 0.500 atm x 75.0 mL0.0500 atm= 7.50 x 102mL(c)V2= 0.500 atm x 75.0 mL555 torr x 1 atm760 torr(d)V2= 0.500 atm x 75.0 mL5.00 torr x 1 atm760 torr(e)V2= 0.500 atm x 75.0 mL5.5 x 10-2torr x 1 atm760 torr= 51.4 mL= 5.70 x 103mL= 5.2 x 105mL12-19(a)Yes. From graphs analogous to A, B, or C in Figure 12-5, but with temperature expressed in oF,we could find the value on the Fahrenheit scale to which the lines extrapolate. This would providethe constant that we could use to convert from the Fahrenheit to the “absolute Fahrenheit” scale.(b)Yes. By the reasoning in part (a), it would not matter what size the degree was; the sameapproach would still give an absolute scale.12-21KoCoFNormal boiling point of water373100.212.Reference for thermodynamic data298.1525.0077.00Dry ice becomes a gas at atmospheric pressure194.6–78.5–109.3The center of the sun (estimated)1.53 x 1071.53 x 1072.75 x 10712-23At approximately 25oC or 298 K, the volume is 20 mL.At approximately 325oC or 598 K, the volume is 40 mL.
10912-25(a)No. The volume is directly proportional to temperature only if the temperature is expressed on anabsolute scale such as the Kelvin scale.(b)V1= 31.0 LT1= 18.0oC + 273.15 = 291.2 KT2= 36.0oC + 273.15 = 309.2 KV1T1= V2T2orV2= V1T2T1= 31.0 L x 309.2 K291.2 K= 32.9 L(c)same as (b), except T2= 400. KV2= V1T2T1= 31.0 L x 400. K291.2 K= 42.6 L(d)Same as (b), except T2= –36oC + 273.15 = 237 KV2= V1T2T1= 31.0 L x 237 K292.2 K= 25.2 L12-27(a)False. Volume is proportional to absolute(Kelvin) temperature, not Celsius temperature.