ch05_lecture_RMJx - Chapter 5 Gases and the Kinetic-Molecular Theory 5-1 Gases and the Kinetic Molecular Theory 5.1 An Overview of the Physical

ch05_lecture_RMJx - Chapter 5 Gases and the...

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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 5.5 The Kinetic-Molecular Theory: A Model for Gas Behavior 5.6 Real Gases: Deviations from Ideal Behavior
5-3 Figure 5.1 The three states of matter.
5-4 Characteristics of Gases 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.
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 Sea level 1 atm 4 miles 0.5 atm 10 miles 0.2 atm 5.2 Atmospheric pressure - the pressure exerted by earth’s atmosphere
5-7 Figure 5.2 Effect of atmospheric pressure on a familiar object.
5-8 Figure 5.3 A mercury barometer. A barometer is used to measure atmospheric pressure. The height of the mercury column is proportional to atmospheric pressure. Units of Pressure 1 torr = 1 mm Hg 1 atm = 760 torr (exactly) 1 atm = 101,325 Pa 760 torr = 101,325 Pa
5-9 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, D h , equals the gas pressure, P gas.
5-10 Figure 5.4 B Open-end manometer. An open-ended manometer is another method of measuring pressure. When P gas is greater than P atm , add D h to P atm . P gas > P atm P gas = P atm + D h
5-11 Table 5.1 Common Units of Pressure
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
5-13 The Gas Laws The gas laws describe the physical behavior of gases in terms of 4 variables: pressure (P) temperature (T) volume (V) amount (number of moles, n) An ideal gas is a gas that exhibits linear relationships among these variables. No ideal gas actually exists , but most simple gases behave nearly ideally at ordinary temperatures and pressures.
5-14 A B
5-15 Figure 5.5 Boyle’s law, the relationship between the volume and pressure of a gas.
5-16 Boyle’s Law At constant temperature, the volume occupied by a

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