Question

Zeolites are :

• A. water softner
• B. catalyst
• C. cation exchanger
• D. all of these

Answer 1

The correct option is D all of these

The catalytic reaction that depends upon the pore structure of the catalyst and the size of the reactant and product molecules is called shape-selective catalysis. Zeolites are good shape selective catalysts because of their honeycomb - like structures. An important zeolite catalyst used in the petroleum industry is ZSM-5. It converts alcohols directly into gasoline (petrol).

Zeolites are used as ion-exchange beds in water purification, softening. zeolites are used to separate molecules (only molecules of certain sizes and shapes can pass through), and as traps for molecules so they can be analyzed. Zeolites are also used as catalysts and sorbents. Their well-defined pore structure and adjustable acidity make them highly active in a large variety of reactions.

So,

Zeolites are water softener as well as catalyst.
They are natural ion exchangers. Permutit water softeners are sodium zeolites.
They take up calcium ions from hard water and release sodium ions in water.
Thus hard water gets softened.
The catalytic action of zeolites is based upon their shape selectivity.
They act as molecular sieves by trapping small molecules (such as water, ammonia, carbon dioxide) in their interstices reversibly.