Question

(a) Write two differences between physical adsorption and chemical adsorption.
(b) Define homogeneous and heterogeneous catalysis. Give an example of each.
(c) Draw labelled diagram of electro-dialysis.

Answer 1

(a) Differences between physical adsorption and chemical adsorption.

Physical adsorption	Chemical adsorption
It involves weak van der Waals forces.	It involves chemical bonds (covalent bonds)
Multilayers of adsorbed particles are formed.	A monolayer of adsorbed particles is formed.

(b) Homogeneous catalysis: A homogeneous catalysis is one in which the catalyst and the reactants exist in the same phase. A homogeneous catalyst dissolves in the gas phase or solution and acts uniformly throughout the gas or solution. Hydrolysis of ethyl acetate by water in an acidic medium to form acetic acid and ethanol is an example of homogeneous catalysis.
Heterogeneous catalysis: A heterogeneous catalysis is one in which the catalyst and the reactants exist in different phases. A heterogeneous catalyst is usually solid and the reactants are in the gas phase or solution. Synthesis of ammonia from nitrogen and hydrogen in presence of an iron catalyst with potassium oxide and aluminium oxide (Haber process) is an example of heterogeneous catalysis.

(c) Labeled diagram of electrodialysis is as shown in the image.