Diffusion Flashcards
It gives the relationship between the diffusivity flux relative to the velocity of the bulk or the diffusion flux relative to a stationary observer
Fick’s Law of Diffusion
The Fick’s law can be identified as diffusion flux relative to:
- Velocity of the bulk
- Stationary observer
In solving the molar flux relative to the stationary observer, it shows that
molar flux = molecular flux + convective flux
Another term for convective flux
phase drift
if the moles A and B are diffusing equally in opposite direction
equimolal counter diffusion
For the ideal gas, concentration can be expressed as
partial pressure
The Fick’s Law of Diffusion gives the rate of diffusion based on
Concentration driving force
In steady state equimolar counterdiffusion, the following is true.
Na=-Nb; Na+Nb=0
The enrichment of ethyl alcohol in the vapor phase from an aqueous ethyl alcohol solution during rectification is an example of:
rectification = equimolar counterdiffusion
Ammonia (A) being absorbed from air (B) into water is an example of:
pag may air = unicomponent
b. Steady state Unicomponent diffusion
For a gas phase, Unicomponent diffusion through a gas-liquid interface will likely occur if:
a. One component is soluble and the other is not
Molecular diffusivity of a liquid
increases with temperature
total mass transferred to mass transferred by molecular diffusion
Sherwood Number
For turbulent mass transfer in pipes, the Sherwood Number depends on the Reynolds number (Re) as:
Re^0.83
A dimensionless number that represents the ratio of the molecular momentum diffusivity to the molecular mass diffusivity.
Schmidt Number
