Understanding Salt Crystal Lattice: Factors Influencing Crystal System Selection

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Discussion Overview

The discussion revolves around the factors influencing the selection of crystal lattice structures in salts, exploring why some salts adopt cubic, hexagonal, or orthorhombic lattices. The conversation touches on concepts of thermodynamics and kinetics in relation to crystal formation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that the choice of crystal lattice is determined by energetic or kinetic favorability, suggesting that thermodynamics and kinetics play a crucial role.
  • Questions arise regarding whether cubic forms crystallize faster than other forms and why cubic forms are considered stable.
  • One participant argues that cubic forms are not universally the most stable, indicating that each compound has its own optimal crystal form.
  • Another participant mentions Ostwald's rule, which states that the least stable form usually crystallizes first, implying a dependence on kinetic control over thermodynamic stability.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the stability and crystallization speed of cubic forms compared to other lattice types. There is no consensus on whether cubic forms are generally faster or more stable, as it appears to depend on the specific compound being crystallized.

Contextual Notes

Limitations in understanding arise from the complexity of factors influencing crystal formation, including the specific properties of different salts and the definitions of stability and speed in crystallization.

jd12345
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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?
 
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jd12345 said:
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.
 
didnt understand that clearly. Does cubic form faster than other forms?
And why is cubic form themost stable?
 
jd12345 said:
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.
 
jd12345 said:
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.
 

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