Which of the following elements is not the constituent of zeolite?

Q. Which of the following elements is not the constituent of zeolite?

1. Al
2. Si
3. O
4. Mg

Answer: Mg

·   Zeolites are the aluminosilicate members of the family of microporous solids known as "molecular sieves" mainly consisting of Si, Al, O, and metals including Ti, Sn, Zn, and so on. The term molecular sieve refers to a particular property of these materials, i.e., the ability to selectively sort molecules based primarily on a size exclusion process. This is due to a very regular pore structure of molecular dimensions.

·   The maximum size of the molecular or ionic species that can enter the pores of a zeolite is controlled by the dimensions of the channels.

·   Zeolites have a porous structure that can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+ and others.

·   These positive ions are rather loosely held and can readily be exchanged for others in a contact solution.

Swedish geologist Axel Cronstedt (1722–1765)—best known as the discoverer of nickel—coined the name "zeolite" because it literally means "boiling stone";

One of the biggest everyday uses for zeolites is in water softeners and water filters. In ion-exchange water softeners, for example, hard water (rich in calcium and magnesium ions) is piped through a column filled with sodium-containing zeolites. The zeolites trap the calcium and magnesium ions and release sodium ions in their place, so the water becomes softer but richer in sodium. Many everyday laundries and dishwasher detergents contain zeolites to remove calcium and magnesium and soften water so they work more effectively.

True or False (About Zeolites)

Zeolites theoretically can be made magnetic by adding sodium ion to them. (False)
Zeolites are used as absorbents only and have no other uses. (False)