Govt. Exams
Entrance Exams
Diffusion is the movement of species due to concentration gradient (molecular level), while convection is the bulk movement of fluid carrying dissolved or suspended species.
Henry's Law constant (P = H*x) represents the equilibrium partial pressure of a gas over a solution, indicating gas solubility in the liquid.
In Langmuir isotherm, q_m represents the maximum (monolayer) adsorption capacity when the adsorbent surface is completely saturated.
The liquid phase mass transfer coefficient k_L has units of m/s or cm/s, representing the rate of mass transfer per unit concentration difference.
Using N_A = K_G * ΔP = 2.5 × 0.8 = 2.0 kmol/(m²·s). This is a direct application of the mass transfer rate equation.
Since mass transfer rate = k_G * a * ΔP, an increase in interfacial area directly increases the mass transfer rate (linear relationship).
Schmidt number (Sc = ν/D_AB) represents the relative importance of momentum diffusion and mass diffusion in a fluid.
Eddy diffusivity (ε_D) accounts for the enhanced mass transfer due to turbulent mixing and eddy formation. Total diffusivity = D_AB + ε_D in turbulent regions.
In evaporative cooling towers, mass transfer is driven by the difference in water vapor concentration between the saturated air at the water surface and the bulk air stream (concentration gradient).
In the Stokes-Einstein equation, r is the molecular radius (or hydrodynamic radius) of the solute particle diffusing through the solvent.
