Impure melting point

[20090900]

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An impure compound will have a lower melting point and higher boiling point, why?

Thanks!

 

[DrRoyal Pains]

Its due to bonding/having the ability to fit into a crystal lattice. If impurities are present, they will disrupt bonding.

 

[Heligrin]

An impure compound will have a lower melting point and higher boiling point, why?

Thanks!

An impure compound will melt at a lower temperature because the impurities will hinder the formation of organized, "perfect," crystals. Think of it as trying to stack squares, but every once in awhile you have to use a sphere.

On the other hand, compounds will have a higher boiling point because the impurities will lower the vapor pressure of the impure liquid. This could be for several reasons, such as inducing VDW forces that would otherwise not exist (induced dipole, ions, etc) (Think of it as adding salt to water -- higher boiling point).

 

[DrRoyal Pains]

👍

 

[thejamespark]

An impure compound will melt at a lower temperature because the impurities will hinder the formation of organized, "perfect," crystals. Think of it as trying to stack squares, but every once in awhile you have to use a sphere.

On the other hand, compounds will have a higher boiling point because the impurities will lower the vapor pressure of the impure liquid. This could be for several reasons, such as inducing VDW forces that would otherwise not exist (induced dipole, ions, etc) (Think of it as adding salt to water -- higher boiling point).

👍