Adsorption Flashcards
concentration of a substance on the surface of a solid or a liquid
adsorption
substance attracted to a surface
absorbate phase
substance to which it is attached
absorbent
factors that determined the amt of gas adsorbed by a solid
- nature of adsorbent and gas na inaabsorbed by a solid
- area of absorbent
- temperature of the gas
- pressure of the gas
Types of adsorption
- physical or van der waal’s adsorption
- chemical or activated adsorption or chemisorption
occurs when the intermolecular
forces of attraction between the fluid molecules and the solid surface are greater than the attractive forces between molecules of the fluid itself.
Physical or Van Der Waal’s Adsorption
Fluid molecules adhere to the surface of the solid adsorbent. The forces responsible for the adsorption are of the same fluid as are involved in the deviation of gases ideal behavior and in liquefaction, i.e. Van der Waal’s forces.
-characterized by low heats of adsorption.
Physical or Van Der Waal’s Adsorption
involves chemical interaction between the adsorbed fluid and the adsorbent solid.
Chemical or Activated Adsorption or Chemisorption
The adsorption is irreversible and it is difficult to separate the adsorbate from the adsorbent. Hence, only physical adsorption tends itself to continuous stage-wise operations.
Chemical or Activated Adsorption or Chemisorption
The ____________________ relates the concentration of the adsorbate in the solution and the adsorbate on the adsorbent at equilibrium at a given temperature.
Freundlich Isotherm
this has binding site where particles come in and there is chemical reaction
chemical adsorption
Freundlich Equation applies to adsorption of solute from
dilute solutions, over a small concentration range
In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is
equal to the heat of wetting
CO2 can be adsorbed by
heated charcoal
lon exchange process is similar to
adsorption
As complete saturation of an adsorbent is approached, the differential heat of
adsorption approaches
heat of normal condensation
The change in enthalpy when a unit quantity of gas is adsorbed by a relatively large quantity of adsorbent (on which a definite concentration of the adsorbed gas already exists) is termed as the
differential heat of adsorption
With an increase in concentration of the adsorbate the integral heat of adsorption
decreases
The change in enthalpy per unit weight of adsorbed gas when adsorbed on a gas-free or “outgassed” adsorbent to form a definite concentration of adsorbate is called its
integral heat of adsorption
In physical adsorption, a gas of
higher molecular weight is adsorbed in preference to a gas of low molecular weight
In physical adsorption, a gas of (pick the wrong)
high critical temperature (this is prolly correct) is adsorbed in preference to a gas of law critical (wrong?) temperature
low volatility is adsorbed in preference to a gas of high volatility
Which of the following adsorbents is used to decolorize yellow glycerine?
activated carbon
When adsorption hysteresis is observed, the desorption equilibrium pressure is
always lower than that obtained by adsorption
Chemisorption (chemical adsorption) is
also called activated adsorption
Physical adsorption is
accompanied by evolution of heat a reversible phenomenon
A unit operation wherein specific components s of a fluid phase (gas or liquid) are preferentially adhered to the surfaces of the solid
adsorption
The adsorbent used in the purification of hydrocarbon products
silica gel
The component adsorbed in adsorption operation is called
adsorbate
A type of adsorption which results in intermolecular forces of attraction between molecules of the solid and the substance adsorbed.
physical adsorption
