Module5Slides(6th) - Chapter 5 Gases and the...

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3/10/12 1 5-1 Chapter 5 Gases and the Kinetic-Molecular Theory 5-2 Gases and the Kinetic Molecular Theory 5.1 An Overview of the Physical States of Matter 5.2 Gas Pressure and Its Measurement 5.3 The Gas Laws and Their Experimental Foundations 5.4 Rearrangements of the Ideal Gas Law 5-3 Distinguishing gases from liquids and solids.An Overview of the Physical States of Matter Gas volume changes significantly with pressure. Solid and liquid volumes are not greatly affected by pressure. Gas volume changes significantly with temperature. Gases expand when heated and shrink when cooled. The volume change is 50 to 100 times greater for gases than for liquids and solids. Gases flow very freely. Gases have relatively low densities. Gases form a solution in any proportions. Gases are freely miscible with each other.
3/10/12 2 5-4 Figure 5.1 The three states of matter. 5-5 Gas Pressure and its Measurement Pressure = force area Atmospheric pressure arises from the force exerted by atmospheric gases on the earth’s surface. Atmospheric pressure decreases with altitude. 5-6 Figure 5.2 Effect of atmospheric pressure on a familiar object.
3/10/12 3 5-7 Figure 5.3 A mercury barometer. 5-8 Figure 5.4 A The Hg levels are equal because both arms of the U tube are evacuated. Closed-end manometer A gas in the flask pushes the Hg level down in the left arm. The difference in levels, Δh, equals the gas pressure, Pgas.5-9 Figure 5.4 B Open-end manometer When Pgasis less than Patm, subtract Δhfrom Patm. Pgas< Patm Pgas= Patm- ΔhWhen Pgasis greater than Patm, add Δhto Patm. Pgas> Patm Pgas= Patm+ Δh
3/10/12 4 5-10 Table 5.1Common Units of Pressure 5-11 Sample Problem 5.1 Converting Units of Pressure PROBLEM: A geochemist heats a limestone (CaCO3) sample and collects the CO2released in an evacuated flask attached to a closed-end manometer. After the system comes to room temperature, Δh= 291.4 mm Hg. Calculate the COpressure in torrs, atmospheres, and kilopascals. PLAN: Construct conversion factors to find the other units of pressure.2
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3/10/12 5 5-13 Boyle’s Law At constant temperature, the volume occupied by a fixed amount of gas is inverselyproportional to the external pressure. V 1 P or PV= constant At fixed Tand n, Pdecreases as Vincreases Pincreases as VdecreasesP1V1= P2V2 5-14

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