Write a short note on zeolites.

Explanation

Zeolites : The three dimensional structure contain no metal ions. If some of the `Si^(+4)` in thein is replaced by `Al^(+3)` and an additional metal ion an infinite three dimensional lattice is formed. Replacements of one or two silicon atoms in `[Si_(2))O_(8)]^(-2n)` . form zeolites. Zeolites act as ion exchanges and as molecular sleves. The structures of zeolites permit the formation of cavities of different sizes. Water molecules and a variety of other molecules like `NH_(3),CO_(2)` and ethanol can be trapped in these cavities. Then zeolites serve as molecular sieves. They trap `Ca^(+2)` ions from hard water and replace them by `Na^(+2)`
Uses of Zeolites :
`to` Zeolites are used as catalysts in petrochemical industries for cracking of hydrocarbons and in Isomerisation
`to` Z5M -5 are is used to convert alcohols directly into gasoline.