Effusion times

Effusion time is proportional to the square root of molar mass. 

The first term on the right-hand side describes [C4H9](f) at the source entrance, here due to pseudo-first-order decay in the reactor with a time constant r, which is the reciprocal of the pseudo-first-order rate coefficient, and the second term is the exit response where tp is the effusion time constant. The solution of this equation is... 

STRATEGY Rate of effusion is inversely proportional to the time taken for a I given volume to effuse the faster the effusion, the less time it takes for a given volume to effuse. We combine that idea with Graham s law to obtain, the relation between the effusion times and the molar masses ... 

EXAMPLE 6-16 Relating Effusion Times and Molar Masses... 

Use the final result and work backward. The molar mass of the unknown is about 4 times as small as that of Kr. Because effusion rate oc 1/V, the unknown will effuse about Vi = 2 times as fast as Kr. The effusion times show that the unknown does indeed effuse 2 times as fast as Kr. 

It is a simple matter now to calculate number of particles per unit area, per unit time, that pass tln-ough a small hole in the wall of the vessel. This quantity is called the rate of effusion, denoted by n, and it governs the loss of particles in a container when there is a small hole in the wall separatmg the gas from a vacuum, say. This number is in fact obtained by integrating the quantity, 8 Af(v) over all possible velocities having the proper direction, and then dividing this number by A5f Thus we find... 

At a given temperature and pressure, die rate of effusion of a gas, in moles per unit time, is inversely proportional to the square root of its molar mass. 

The time required for effusion is inversely related to rate. 

A gas effuses 1.55 times faster than propane (C3H8) at the same temperature and pressure. 

If 0.0129 mol of N204 effuses through a pinhole in a certain amount of time, how much NO would effuse in that same amount of time under the same conditions ... 

Because the times it takes for the same amount of two substances to effuse through a small hole are inversely proportional to the rates at which they effuse, an equivalent statement is... 

This relation can be used to estimate the molar mass of a substance by comparing the time required for a given amount of the unknown substance to effuse with that required for the same amount of a substance with a known molar mass. 

What is the molar mass of a compound that takes 2.7 times as long to effuse through a porous plug as it did for the same amount of XeF, at the same temperature and pressure ... 

A sample of argon gas effuses through a porous plug in 147 s. Calculate the time required for the same number of moles of (a) CO, (b) C2H4, (c) H2, and (d) SO, to effuse under the same conditions of pressure and temperature. 

When 2.36 g of phosphorus was burned in chlorine, the product was 10.5 g of a phosphorus chloride. Its vapor rook 1.77 times as long to effuse as the same amount of CO, under... 

Because the ratio is so close to 1, the vapor must be allowed to effuse repeatedly through porous barriers consisting of screens with large numbers of minute holes. In practice, it is allowed to do so thousands of times. 

The age of Green tuff volcanic activity ranges widely from ca. 25 Ma to 2 Ma. Volcanic activity during the early to middle Miocene (25-15 Ma) was intensive, whereas it was weak during the late Miocene to early Quaternary (Sugimura et al., 1963) (Fig. 3.1). The production of lavas and other effusives per unit time reached five or six time more... 

The number of washings may be reduced to about twenty, if time is allowed for Effusion of the alkali from the surface of the catalyst into the surrounding wash water. Use 750 ml. of water in each waslung, aUow diffusion to proceed for 3-10 minutes, stir again, and decant the supernatant liquid as soon as the catalyst settles to the bottom. 

Use of systemic corticosteroids is discouraged in patients with OA. However, in a subset of patients with an inflammatory component or knee effusion involving one or two joints, intraarticular corticosteroids can be useful as monotherapy or as an adjunct to analgesics. The affected joint can be aspirated and subsequently injected with a corticosteroid. The aspirate should be examined for the presence of crystalline formation and infection. A single joint should not be injected more than three to five times per year. 

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