Which explains the diffusion of gases

If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Please consult the latest official manual style if you have any questions regarding the format accuracy. The reader understands the diffusion of gases in the lung.

Distinguishes between perfusion limitation and diffusion limitation of gas transfer in the lung. Describes the diffusion of oxygen from the alveoli into the blood. Describes the diffusion of carbon dioxide from the blood to the alveoli. Defines the diffusing capacity and discusses its measurement. Interprets standard pulmonary function test PFT data.

Diffusion of a gas occurs when there is a net movement of molecules from an area in which that particular gas exerts a high partial pressure to an area in which it exerts a lower partial pressure.

During bulk flow, gas movement results from differences in total pressure, and molecules of different gases move together along the total pressure gradient. During diffusion, different gases move according to their own individual partial pressure gradients.

Gas transfer during diffusion occurs by random molecular movement. It is therefore dependent on temperature because molecular movement increases at higher temperatures. In a static situation, diffusion continues until no partial pressure differences exist for any gases in the 2 areas; in the lungs, oxygen and carbon dioxide continuously enter and leave the alveoli, and so such an equilibrium does not take place.

Oxygen is brought into the alveoli by bulk flow through the conducting airways. When air flows through the conducting airways during inspiration, the linear velocity of the bulk flow decreases as the air approaches the alveoli. If someone is cooking in the kitchen, the smell travels around the house to other rooms.

This is because of diffusion , the movement of particles from an area of high concentration to an area of low concentration. For diffusion to work, the particles must be able to move around. This means that diffusion does not happen in solids — the particles in a solid can only vibrate and cannot move from place to place. Diffusion is driven by differences in concentration.

When chemical substances such as perfume are let loose in a room, their particles mix with the particles of air. The particles of smelly gas are free to move quickly in all directions. The barrier must have tiny, uniform holes about 10 —6 cm in diameter and be porous enough to produce high flow rates. All materials the barrier, tubing, surface coatings, lubricants, and gaskets need to be able to contain, but not react with, the highly reactive and corrosive UF 6.

Because gaseous diffusion plants require very large amounts of energy to compress the gas to the high pressures required and drive it through the diffuser cascade, to remove the heat produced during compression, and so on , it is now being replaced by gas centrifuge technology, which requires far less energy. A current hot political issue is how to deny this technology to Iran, to prevent it from producing enough enriched uranium for them to use to make nuclear weapons.

Gaseous atoms and molecules move freely and randomly through space. Diffusion is the process whereby gaseous atoms and molecules are transferred from regions of relatively high concentration to regions of relatively low concentration.

Effusion is a similar process in which gaseous species pass from a container to a vacuum through very small orifices. Explain why the numbers of molecules are not identical in the left- and right-hand bulbs shown in the center illustration of Figure.

Effusion can be defined as the process by which a gas escapes through a pinhole into a vacuum. Calculate the relative rates of diffusion of H 2 O and D 2 O. Which of the following gases diffuse more slowly than oxygen? During the discussion of gaseous diffusion for enriching uranium, it was claimed that UF 6 diffuses 0. Show the calculation that supports this value. Calculate the relative rate of diffusion of 1 H 2 molar mass 2.

A gas of unknown identity diffuses at a rate of Calculate the molecular mass of the unknown gas. Estimate the molar mass of the unknown gas. Gaseous diffusion has been used to produce enriched uranium for use in nuclear power plants and weapons.

Naturally occurring uranium contains only 0. In a gaseous diffusion enrichment plant, uranium hexafluoride UF 6 , the only uranium compound that is volatile enough to work is slowly pumped through large cylindrical vessels called diffusers, which contain porous barriers with microscopic openings.

The process is one of diffusion because the other side of the barrier is not evacuated. The UF 6 molecules have a higher average speed and diffuse through the barrier a little faster than the heavier UF 6 molecules. The gas that has passed through the barrier is slightly enriched in UF 6 and the residual gas is slightly depleted. The small difference in molecular weights between UF 6 and UF 6 only about 0. But by connecting many diffusers in a sequence of stages called a cascade , the desired level of enrichment can be attained.

Although the theory is simple, this required surmounting many daunting technical challenges to make it work in practice. The barrier must have tiny, uniform holes about 10 —6 cm in diameter and be porous enough to produce high flow rates. All materials the barrier, tubing, surface coatings, lubricants, and gaskets need to be able to contain, but not react with, the highly reactive and corrosive UF 6. Because gaseous diffusion plants require very large amounts of energy to compress the gas to the high pressures required and drive it through the diffuser cascade, to remove the heat produced during compression, and so on , it is now being replaced by gas centrifuge technology, which requires far less energy.

A current hot political issue is how to deny this technology to Iran, to prevent it from producing enough enriched uranium for them to use to make nuclear weapons. Gaseous atoms and molecules move freely and randomly through space. Diffusion is the process whereby gaseous atoms and molecules are transferred from regions of relatively high concentration to regions of relatively low concentration. Effusion is a similar process in which gaseous species pass from a container to a vacuum through very small orifices.

At approximately what distance from the ammonia moistened plug does this occur?