Understanding Salt Crystal Lattice: Factors Influencing Crystal System Selection

[jd12345]

What decides that which salt will take up which crystal lattice?
Some salts have cubic lattice , some have hexagonal , some have orthorhombic - but what factor decides which crystal system the salt will take over. Most of the examples i have seen consist of cubic lattice system. Is it becasue it is the most symmetrical?

 

[chemisttree]

What decides that which salt will take up which crystal lattice?
Some salts have cubic lattice , some have hexagonal , some have orthorhombic - but what factor decides which crystal system the salt will take over. Most of the examples i have seen consist of cubic lattice system. Is it becasue it is the most symmetrical?

It is because it is most energetically favorable or kinetically favorable. Thermodynamics and kinetics determine crystal form.

 

[jd12345]

didnt understand that clearly. Does cubic form faster than other forms?
And why is cubic form themost stable?

 

[Borek]

didnt understand that clearly. Does cubic form faster than other forms?
And why is cubic form themost stable?

No, it is not a general case of cubic being the most stable. Each compound has its own "best" crystal form.

 

[chemisttree]

didnt understand that clearly. Does cubic form faster than other forms?
And why is cubic form themost stable?

I don't know if cubic forms faster than other forms or if it is more stable. It would depend on that which is being crystallized.

Read more here. Notice that Ostwald's rule states that the least stable form usually crystallizes first. That tendency is obviously under kinetic control more so than thermodynamic.