Q.Write a note on zeolites.

Step 1. Zeolites are three-dimensional crystalline solids containing aluminium, silicon and oxygen arranged in a regular three-dimensional framework -- specifically, hydrated sodium aluminosilicates of general formula Na₂O.Al₂O₃.x(SiO₂).yH₂O (x = 2 to 10; y = 2 to 6).

Step 2. Structurally, the silicon and aluminium atoms are tetrahedrally coordinated to each other through shared oxygen atoms, building a genuinely rigid framework; within this framework, the monovalent sodium ions and water molecules are held only loosely.

Step 3. Viewed as a whole, a zeolite crystal has a honeycomb-like appearance, made up of a network of interconnected tunnels and cages; water molecules can move freely in and out through these pores while the surrounding framework itself stays completely rigid and unchanged.

Step 4. Because the pore/channel sizes across a given zeolite crystal are nearly uniform, the framework can act as a molecular sieve, admitting or excluding other molecules essentially on the basis of their size. …

State the general formula and structural framework of a zeolite, describe its porous/molecular-sieve behaviour, and con …

• Describing zeolites only as 'a mineral used to soften water' without explaining WHY -- the ion-exchange mechanism (loosely-held Na⁺ swapping for Ca²⁺/Mg²⁺ within the …