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Chapter 5
Gases
5.1
Title
 Molecular motion in a gas
Caption
 The molecules in a gas are in constant motion. The purple balls represent gaseous atoms that collide with each other and the walls of the container. Gas molecules are in constant motion. "Pressure" is a measure of the collisions of the atoms with the container.
Keywords
 gas, pressure, model, KMT
5.2
Title
 Measurement of air pressure w/a mercury barometer
Caption
 (a) The mercury levels are equal inside and outside the open-end tube because the tube is open to the atmosphere and filled with air. (b) A column of mercury 760 mm high is maintained in the closed-end tube for standard atmospheric pressure. The space above the mercury is devoid of air (a vacuum), containing only a tiny trace of mercury vapor.
Keywords
 pressure, barometer, atmosphere
5.3
Title
 Measuring gas pressure with a closed-end mannometer
Caption
 The gas pressure is equal to the difference in height (Dh) of the mercury column in the two arms of the manometer.
Keywords
 pressure, manometer, barometer, gas
5.4
Title
 Measuring gas pressure with an open ended mannometer
Caption
 The difference in mercury levels (Dh) between the two arms of the manometer gives the difference between barometric pressure and the gas pressure.
Keywords
 pressure, manometer, barometer, gas
5.5abcd
Title
 A conceptual example of gas pressures
Caption
 As an exercise, one can order the drawings in order of increasing pressures without doing calculations.
Keywords
 pressure, manometer, barometer, example, gas
5.6
Title
 Boyle's law: A kinetic-thory view and a graphical representation
Caption
 As the pressure is successively reduced from 4.00 atm to 2.00 atm and then to 1.00 atm, the volume doubles and then doubles again. The volume is inversely proportional to the pressure, and the pressure-volume product is a constant (PVÊ=Êa).
Keywords
 boyle's law, gas, pressure, volume
5.8
Title
 Charles' law: Gas volume as a function of temperature
Caption
 The gas shown has a volume of 60 mL at about 70 ¡C. When the gas is cooled through the temperature interval from about 70 ¡C toÊ-100 ¡C, its volume drops to 30 mL. The gas volume continues to decrease in a linear fashion as the temperature is lowered. The extrapolated line intersects the temperature axis (corresponding to a volume of zero) at about -270 ¡C.
Keywords
 Charles law, temperature, volume, gas
5.11
Title
 The effect of temperature on the pressure of a fixed amount of gas in a constant volume: A kinetic theory interpretation
Caption
 The amount of gas and its volume are the same in either case, but if the gas in the ice bath (0 ¡C) exerts a pressure of 1 atm, the gas in the boiling-water bath (100 ¡C) exerts a pressure of 1.37 atm. The frequency and the force of the molecular collisions with the container walls are greater at the higher temperature.
Keywords
 gas, pressure, temperature, volume, kinetic theory
5.12
Title
 Gay-Lussac's law of combining volumes
Caption
 Gay-Lussac's law of combining volumes states that When gases measured at the same temperature and pressure are allowed to react, the voluems of gaseous reactants and products are in small whole-number ratios.
Keywords
 Gay-lussac, gas, chemical reaction, volume
5.13
Title
 Avogadro's explanation of Gay-Lussac's law of combining volumes
Caption
 When the gases are measured at the same temperature and pressure, each of the identical flasks contains the same number of molecules. Notice how the combining ratio: 2 volumes H2 to 1 volume O2 to 2 volumes H2O leads to a result in which all the atoms present initially are accounted for in the product.
Keywords
 volume, gas, chemical reaction, avogadro, gay-lussac
5.14
Title
 Dalton's law of partial pressures illustrated
Caption
 Each gas expands to fill the container and exerts a pressure that is readily calculated using the ideal gas equation. The total pressure of the mixture of gases is equal to the sum of the partial pressures of the individual gases.
Keywords
 partial pressure, Dalton's law, volume, pressure, gas
5.16
Title
 Collection of a gas over water
Caption
 To make the total pressure of the gaseous mixture in the bottle equal to the atmospheric pressure as measured with a barometer, it is necessary to adjust the position of the bottle so that the water levels inside and outside the bottle are the same. When this is done, the partial pressure of the gas is given by: Pgas = Pbar - PH2OPbar is the barometer reading and the vapor pressure of water is obtained from tabulated data such as Table 5.4.
Keywords
 pressure, vapor pressure, barometric pressure, gas
5.17
Title
Caption
 At 273 K, the most probable speeds for O2 and H2 molecules are 377 and 1500 m/s, respectively. Notice that the temperature must be greater than 1000 K before O2 molecules have the same most probable speed as do H2 molecules at 273 K (see Exercise 5.22).
Keywords
 kinetic theory, gas, temperature
5.18
Title
 Diffusion of gases
Caption
 Molecules of HCl diffuse from the bottle of hydrochloric acid on the left, while NH3 molecules diffuee from the ammonia solution on the right. Where the two gases meet, they react to form white ammonium chloride, which appears as "smoke." The microscopic view shows hat the lighter ammonia molecules (mass = 17u) move- and diffuse- faster than the heavier HCl molecules (mass = 36.5u). Note that the smoke in the photo is closer to the HCl bottle. The ammonia molecules have diffused farther than the HCl molecules in the same period of time.
Keywords
 gas, diffusion, kinetic theory, energy, model
5.19
Title
 Intermolecular forces of attractions
Caption
 Attractive forces of the orange molecules for the purple molecule cause the purple molecule to exert less force when it collides with the wall than it would if these attractive forces did not exist.
Keywords
 ideal gas, real gas, van der waals, intermolecular forces, gas, pressure
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