Kinetic-molecular theory effusion

The connection between temperature and kinetic energy obtained from the kinetic-molecular theory makes it possible to calculate the average speed of a gas particle at any temperature. An important practical consequence of this relationship is Graham s law, which states that the rate of a gas s effusion, or spontaneous passage through a pinhole in a membrane, depends inversely on the square root of the gas s mass. 

Diffusion and effusion According to the kinetic-molecular theory, there are no significant forces of attraction between gas particles. Thus, gas particles can flow easily past each other. Often, the space into which a gas flows is already occupied by another gas. The random motion of the gas particles causes the gases to mix until they are evenly distributed. Diffusion is the term used to describe the movement of one material through another. The term may be new, but you are probably familiar with the process. If you are in the den, can you tell when someone sprays perfume in the bedroom Perfume particles released in the bedroom diffuse through the air until they reach the den. Particles diffuse from an area of high concentration (the bedroom) to one of low concentration (the den). 

Graham s law of effusion (p. 387) hydrogen bond (p. 395) kinetic-molecular theory (p. 385)... 

The Process of Effusion One of the early triumphs of the kinetic-molecular theory was an explanation of effusion, the process by which a gas escapes from its container through a tiny hole into an evacuated space. In 1846, Thomas Graham studied this process and concluded that the effusion rate was inversely proportional to the square root of the gas density. The effusion rate is the number of moles (or molecules) of gas effusing per unit time. Because density is directly proportional to molar mass, we can state Graham s law of effusion as follows the rate of effusion of a gas is inversely proportional to the square root of its molar mass,... 

Understand the kinetic-molecular theory and how it explains the gas laws, average molecular speed and kinetic energy, and the processes of effusion and diffusion ( 5.6) (SP 5.13) (EPs 5.53-5.65)... 

Required Knowledge (1) The behavior of gases. (2) The kinetic-molecular theory. (3) The qualitative understanding of Graham s Law of Effusion. 

We observe that the kinetic-molecular theory helps us account for such gas properties as effusion, movement through tiny openings, and diffusion, movement through another substance. 

KINETIC-MOLECULAR THEORY OF GASES EFFUSION AND DIFFUSION (sections 10.7 and 10.8)... 

MOLECULAR EFFUSION AND DIFFUSION (SECTION 10.8) It Mows from kinetic-molecular theory that the rate at which a gas undergoes effusion (escapes through a tiny hole) is inversely proportional to the square root of its molar mass (Graham s law). The diffusion of one gas through the space occupied by a second gas is another phenomenon related to the speeds at which molecules move. Because moving molecules undergo frequent collisions with one another, the mean free path—the mean distance traveled between collisions—is short. Collisions between molecules limit the rate at which a gas molecule can diffuse. 

We will see how the kinetic molecular theory of gases, which is based on the properties of individual molecules, can be used to describe macroscopic properties such as the pressure and temperature of a gas. We learn that this theory enables us to obtain an expression for the speed of molecules at a given temperature, and understand phenomena such as gas diffusion and effusion. (5.7)... 

Atmospheric pressure, p. 176 Effusion, p. 209 Kinetic molecular theory of Standard atmospheric pressure... 

Key Terms Kinetic-molecular theory (KMT) Ideal gas Diffusion Effusion Graham s law of effusion... 

The kinetic-molecular theory explains that, at a given temperature and pressure, the gas with the lower molar mass effuses faster because the most probable speed of its molecules is higher therefore, more molecules escape per unit time. 

Kinetic Molecular Theory of Gases Macroscopic properties like pressure and temperature of a gas can be related to the kinetic motion of molecules. The kinetic molecular theory of gases assumes that the molecules are ideal, the number of molecules is very large, and that their motions are totally random. Both gas diffusion and gas effusion demonstrate random molecular motion and are governed by the same mathematical laws. 

How the Kinetic-Molecular Theory Explains the Gas Laws 170 Effusion and Diffusion 175... 

The random motion of gas molecules gives rise to two readily observable phenomena diffusion and effusion. Diffusion is the mixing of gases as the result of random motion and frequent collisions (Figure 11.20), while effusion is the escape of gas molecules from a container to a region of vacuum (Figure 11.21). One of the earliest successes of the kinetic molecular theory was its ability... 

The kinetic molecular theory also allows us to predict the mean free path of a gas particle (the distance it travels between collisions) and relative rates of diffusion or effusion. 

Gas Properties Relating to the Kinetic-Molecular Theory— The diffusion and effusion of... 

As a consequence of these simple deductions, Graham s experiments c effusion through an orifice came to be regarded as one of the earliest direct experimental checks on the kinetic theory of gases. However, a closer examination of his experimental conditions reveals that this view is mistaken. As mentioned earlier, his orifice diameters ranged upwards from 1/500 in., while the upstream pressure was never very much less thai atmospheric. Under these circumstances the molecular mean free path len ... 

---