Real Gases Deviations from Ideal Behavior

91 Real Gases Deviations from Ideal Behavior 

The extent to which a real gas departs from ideal behavior can be seen by rearranging the ideal-gas equation to solve for n  

Deviation from ideal behavior also depends on temperature. As temperature increases, the behavior of a real gas more nearly approaches that of the ideal gas 

True or false Nitrogen gas behaves more like an ideal gas as the temperature increases. 

Gas molecules occupy a small fraction of the total volume. 

Because of molecular coUisioris, the direction of motion of a gas molecule is constantly changing. Therefore, the diffusion of a molecule from one point to another consists of many short, straight-line segments as collisions buffet it around in random directions ( FIGURE 10.21). 

Will these changes increase, decrease, or have no effect on the mean free path of the moiecuies in a gas sample  

9 REAL GASES DEVIATIONS FROM IDEAL BEHAVIOR 

A FIGURE 10.21 Diffusion of a gas mofecule. For clarity, no other gas molecules in the container are shown. 

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Ideal gases obey the ideal gas law at all temperatures and pressures. However, there are no ideal gases, only real gases. Real gases deviate from ideal behavior most strongly at high pressures and/or low temperatures. So, where do the basic tenets of Kinetic Molecular Theory fail ... 

You should be aware of how real gases deviate from ideal behavior. Van der Waals equation ... 

REAL GASES DEVIATIONS FROM IDEAL BEHAVIOR We learn that real gases deviate from ideal behavior because the gas molecules have finite volume and because attractive forces exist between molecules. The van der Waab equation gves an accurate account of real gas behavior at high pressures arxJ low temperances. 

SECTION 10.9 Real Gases Deviations from Ideal Behavior... 

The basic assumptions of the kinetic-molecular theory of gases give us insight into why real gases deviate from ideal behavior. The molecules of an ideal gas are assumed to occupy no space and have no attraction for one another. Real molecules, however, do have finite volumes and do attract one another. As Figure 10.21 shows, the unoccupied space in which real molecules can move is less than the container volume. At low pressures, the combined volume of the gas molecules is negligible relative to the container volume. Thus, the unoccupied volume available to the molecules is essentially the container volume. 

REAL GASES DEVIATIONS FROM IDEAL BEHAVIOR (SECTION 10.9) Departures from ideal behavior increase in magnitude as pressure increases and as temperature decreases. Real gases depart from ideal behavior because (1) the molecules possess finite volume and (2) the molecules experience attractive forces for one another. These two effects make the volumes of real gases larger and their pressures smaller than those of an ideal gas. The van der Waals equation is an equation of state for gases, which modifies the ideal-gas equation to account for intrinsic molecular volume and intermolecular forces. 

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