6.adsorption.doc

DAY 2: CHEMICAL ENGINEERING – Adsorption

ADSORPTION Review Questions

1.

Physical adsorption is a. an irreversible phenomenon b. a reversible phenomenon c. accompanied by evolution of heat d. both b and c

2.

Chemisorption (chemical adsorption) is a. same as “Van der Waals” adsorption b. characterized by adsorption of heat c. also called activated adsorption d. none of these

3.

Rate of adsorption increases as the a. temperature increases b. temperature decreases

c. pressure decreases d. size of adsorbent increases

4.

When adsorption hysteresis is observed, the desorption equilibrium pressure is a. always lower than that obtained by adsorption b. always higher than that obtained by adsorption c. same as that obtained by adsorption d. dependent on the system can be either lower or higher than that obtained by adsorption

5.

Which of the following adsorbent is used to decolorize yellow glycerine? a. silica gel c. Fuller’s earth b. alumina d. activated carbon

6.

Freundlich equation applies to adsorption of solute from a. dilute solutions, over a small concentrated range b. gaseous solutions at high pressure c. concentrated solutions d. none of these

7.

In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is a. equal to the heat of formation of surface compound b. equal to the heat of wetting c. zero d. called integral heat of adsorption

8.

Pick out the wrong statement Generally for physical adsorption, a gas of a. higher molecular weight is adsorbed in preference to a gas of low molecular weight b. high critical temperature is adsorbed in preference to a gas of low critical temperature c. low volatility is adsorbed in preference to a gas of high volatility d. both b and c

9.

The change in enthalpy per unit weight of adsorbed gas when adsorbed on gas free or “outgassed” adsorbent to form a definite concentration of adsorbate is called its a. integral heat of adsorption b. heat of wetting c. differential heat of adsorption d. heat of normal condensation

DAY 2: CHEMICAL ENGINEERING – Adsorption

10. With increase in concentration of the adsorbate the integral heat of adsorption a. increases b. decreases c. remains unchanged d. may increase or decrease; depends on type of adsorbate 11. 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 a. differential heat of adsorption c. integral heat of adsorption b. heat of wetting d. heat of normal condensation 12. As complete saturation of an adsorbent is approached, the differential heat of adsorption approaches a. heat of normal condensation c. zero b. integral heat of adsorption d. none of these 13. Ion exchange process is similar to a. absorption b. extraction

c. adsorption d. leaching

14. CO2 can be adsorbed by a. hot cupric oxide b. heated charcoal

c. Cold Ca (OH)2 d. alumina