crystalline nature

[anigeo]

is it necessary that all crystalline solids are hydrated or hygroscopic.
could anyone explain me the case of NACl and NA2CO3.10H2O?

[jedishrfu]

could you be a little more description as to what you're investigating you know some context for your question?

[Borek]

http://en.wikipedia.org/wiki/File:Quartz,_Tibet.jpg

http://upload.wikimedia.org/wikipedia/commons/thumb/1/14/Quartz%2C_Tibet.jpg/479px-Quartz%2C_Tibet.jpg

No crystalline water, not hygroscopic.

Does it answer your question?

[anigeo]

is it so that Na2CO3.10H2O crystalline and Na2CO3 not?if not what it is.

[Borek]

is it so that Na2CO3.10H2O crystalline and Na2CO3 not?if not what it is.

Please elaborate, I don't understand your question.

Many substances will contain crystalline water when crystallized from water solutions, and it can be difficult to prepare their anhydrous crystals. In such cases it may mean anhydrous crystals will be very hygroscopic. It doesn't mean every crystal of every substance contains crystalline water and is hygroscopic, as is clearly shown by the quartz example.

[AbedeuS]

Some chemicals just tend to have a high affinity to water. So in the case of your Na2CO3 it may well have been crystallized from water or in a wet environment and its affinity for water dictates that the lowest energy pathway to crystallization just so happens to include any nearby water molecules.

You could equally crystallize them in anhydrous conditions but the resulting anhydrous, crystalline, substance is still the same chemical and as such still has its affinity for water which makes it a hygroscopic material.

[anigeo]

Please elaborate, I don't understand your question.

Many substances will contain crystalline water when crystallized from water solutions, and it can be difficult to prepare their anhydrous crystals. In such cases it may mean anhydrous crystals will be very hygroscopic. It doesn't mean every crystal of every substance contains crystalline water and is hygroscopic, as is clearly shown by the quartz example.

thanks i just thought that anhydrous crystals can never be produced.