Surface Chemistry Part - 1

Which of the following process does not occur at the interface of phases?

• crystallisation

• heterogenous catalysis

• homogeneous catalysis

• corrosion

At the equilibrium position in the process of adsorption ___________.

• $\Delta$ H > 0

• $\Delta$ H = T $\Delta$ S

• $\Delta$ H > T $\Delta$ S

• $\Delta$ H < T $\Delta$ S

The term ‘sorption’ stands for ____________.

• (i) absorption

• (ii) adsorption

• (iii) both absorption and adsorption

• (iv) desorption

Extent of physisorption of a gas increases with ___________.

• (i) increase in temperature.

• (ii) decrease in temperature.

• (iii) decrease in surface area of adsorbent.

• (iv) decrease in strength of van der Waals forces.

Which of the following is not a favourable condition for physical adsorption?

• high pressure

• negative $\Delta$ H

• higher critical temperature of adsorbate

• high temperature

Physical adsorption of a gaseous species may change to chemical adsorption with ______________.

• decrease in temperature

• increase in temperature

• increase in surface area of adsorbent

• decrease in surface area of adsorbent

Which of the following is an example of absorption?

• Water on silica gel

• Water on calcium chloride

• Hydrogen on finely divided nickel

• Oxygen on metal surface

Extent of adsorption of adsorbate from solution phase increases with ________.

• increase in amount of adsorbate in solution.
  

• decrease in surface area of adsorbent

• increase in temperature of solution.

• decrease in amount of adsorbate in solution

Which one of the following is not applicable to the phenomenon of adsorption?

• $\Delta$ H > 0

• $\Delta$ G < 0

• $\Delta$ S < 0

• $\Delta$ H < 0

In physisorption adsorbent does not show specificity for any particular gas because ______________.

• involved van der Waals forces are universal.

• gases involved behave like ideal gases.

• enthalpy of adsorption is low.

• it is a reversible process.