Unit Operations - Diffusion

equimolal counter-diffusion

The enrichment of ethyl alcohol in the vapor phase from an aqueous ethyl alcohol solution during rectification is an example of

volume-mean velocity of components A and B

The diffusivity of a binary system as given in the equation of Fick's Law is usually measured relative to the

has a physical meaning and can be measured

The diffusivity of a component A relative to itself, that is Daa

the Prandtl Number is unity

The Reynolds Analogy is applied when

mass transfer area

The molar flux of component A in molecular diffusion is independent of

none of these

A dimensionless number that represents the ratio of the mass transferred by molecular diffusion to the total mass transferred is

phase drift + molecular diffusion

The molar diffusion flux of A relative to a stationary plane is a combination of

concentration driving force

The Fick's Law of Diffusion gives the rate of diffusion based on

bulk in terms of moles is not moving

Equimolar counter-diffusion means that the

one component is soluble and the other is not

For a gas phase diffusion, unicomponent diffusion through a gas-liquid interface will likely to occur if

the flow rate of gas and liquid

The rate of mass transfer of component A through an interface in a turbulent flow system is less affected by

logarithmic

For binary unicomponent diffusion, the concentration profile of the diffusing component along the diffusion path is

no convective flux or phase drift is involved

The transport analogy among mass, heat and momentum transfers is complete when

the mass transfer area can be measured accurately

A wetted-wall column is usually used to determine the mass transfer coefficient experimentally because

Kinetic Theory of Gases

It provides the basis for the quantitative description of the diffusional phenomena of molecules

eddy diffusion

The method of solute transfer which involves rapid movement of large chunks of fluid in turbulent motion

steady state unicomponent diffusion

Ammonia (A) being absorbed from air (B) into water is an example of

Na= -Nb ; Na + Nb is zero

In steady-state equimolal counter-diffusion, the following are true:

the bulk motion of the phase

The flux of A in unicomponent diffusion is different from that of equimolal counter-diffusion because of

Sherwood Number

It represents the total mass transferred to mass transferred by molecular diffusion

diffusion coefficient

It is a measure of the diffusive mobility of individual molecules in solution